disclosed herein is a stroller with a secondary attachment structure . although the secondary attachment may form any structure suitable for use with a stroller , the secondary attachment and mechanisms for attaching it to the stroller are discussed within the context of specific embodiments . in one embodiment the secondary attachment may comprise an infant car seat adapter . in another embodiment the secondary attachment comprises a basket . these embodiments are not intended to limit the invention or the claims , but instead to provide context and examples of the secondary attachment . in general , the stroller system of the present disclosure comprises two generally mirror - imaged structural frames connected to each other by cross members . as the cross members may be placed in any suitable position to connect the opposing sides of the stroller , and since the structural frame members are generally mirror images , the discussion of the structure of the present disclosure will focus on a single frame , or side portion of the stroller . one skilled in the art will recognize that the description will apply equally to the mirrored frame , and the present disclosure is intended to apply equally to opposing frame members of the stroller . as illustrated in fig1 , a stroller 100 has a base 105 having a first ( front ) end 105 a , a second ( rear ) end 105 b and an elongated portion 105 c extending therebetween . a first ( front ) frame member 101 having a first lower end 101 a and a second upper end 101 b is connected to the base 105 proximate the first end 105 a of the base 105 . a generally elongated portion extends between the first lower end 101 a and the second upper end 101 b of the first front frame member 101 . as will be discussed in more detail below , the second upper end 101 b of the first front frame member 101 has at least one structural member configured to provide support for a secondary attachment . as depicted , in one embodiment the secondary attachment is a basket 137 . a second rear frame member 103 having a first lower end 103 a and a second upper end 103 b is also connected to the base 105 proximate the second end 105 b of the base 105 . the second frame member 103 has a generally elongated portion which extends between the first lower end 103 a and the second upper end 103 b of the second rear frame member 103 b . the second upper end 103 b of the second rear frame member 103 has at least one structural member 111 also configured to provide support for the secondary attachment 137 . a handle 109 may be attached to the second upper end 103 b of the second rear frame member 103 b . fig2 presents a side perspective view of the second portion 103 b of the second frame member 103 taken from the interior of the stroller . fig2 illustrates a structural member 111 adapted to receive a portion of a secondary attachment 123 located at the connection between the second upper end 103 b of the second rear frame member 103 and handle 109 . the structural member 111 has a receptacle unit 113 with two receptacles 115 . each receptacle 115 is capable of receiving at least one of the attachment ends 117 of the secondary attachment ( which , in the embodiments shown is an infant car seat adapter ) 123 , and has an opening generally oriented towards the top surface of the receptacle 115 . in one embodiment , the secondary attachment 123 may form a substantially rectangular frame . the perpendicular corners of the frame may be connected by a connector piece 119 , with a protruding attachment end 117 . alternatively , the secondary attachment 123 may be of unitary construction or have some other configuration . in fig2 the secondary attachment 123 is detached from the second rear frame member . the connector piece 119 may be configured to allow rotation of the perpendicular elements of the rectangular frame with respect to the other . the receptacles 115 are generally semi - circular in nature ; however , each receptacle may have one or more rounded tabs 116 or other protrusions located proximate the open end of the semicircle to facilitate snapping of the attachment ends into the receptacle . fig3 illustrates the secondary attachment 123 of fig2 , in a second configuration where the secondary attachment 123 is attached to the stroller , with the attachment ends 117 of the secondary attachment engaged with their respective receptacles 115 . the attachment ends 117 may be substantially cylindrical in shape . in one embodiment , the attachment ends 117 may engage with their respective receptacles 115 and be held in place by a primary locking mechanism . the primary locking mechanism may include the rounded tabs 116 , a spring loaded pin ( not shown in fig3 ) or some other locking means . in one embodiment , a one - step , two - handed method may be used to position and lock the secondary attachment 123 into the frame members . the secondary attachment 123 may be aligned with the openings of the receptacles 115 and it may lock into place once the secondary attachment is lowered into the receptacle 117 . the secondary attachment 123 may be attached to the stroller using spring loaded pins which are biased to deploy , and are retracted by an actuator such that the attachment ends 117 can engage with the receptacles . fig4 illustrates a secondary attachment 123 in a first position , disengaged from the stroller . the secondary attachment 123 of fig4 has a secondary locking mechanism that includes a casing 121 attached to the secondary attachment 123 . the casing 121 is positioned and shaped with a generally rounded shape to which facilitates rotation of the secondary attachment 123 about the opening or the receptacle 115 or the frame member , when the attachment end 117 is disposed in the receptacle , such that the casing 121 rotates about the receptacle 115 , thereby locating the receptacle 115 at least partially between the attachment end 117 and the casing 121 . as a result , the secondary attachment 123 can no longer be detached from the stroller by lifting it upwards . in one embodiment the casing 121 may be attached to the frame member , with other engaging protrusions located on the secondary attachment . fig5 illustrates a secondary attachment 123 in a second position , engaged with the receptacle 117 buy prior to a rotating the secondary attachment to a position where the casing 121 prevents the secondary attachment 123 from being removed from the stroller . fig6 illustrates the secondary attachment 123 in a first position , similar to that of fig5 , where the secondary attachment 123 is attached to the stroller at the upper portion of the rear frame member 103 b by placing the attachment end 117 in the receptacle 115 . fig7 illustrates the secondary attachment 123 with an exemplary infant car seat adapter in a second position where the secondary attachment 123 is rotated downwards about the attachment end 117 and receptacle 115 , such that the attachment ends 118 may be aligned with the receptacles 125 on upper portion of the first frame member 101 b . fig8 illustrates the secondary attachment 123 engaged with both the first front frame member 101 b and the second rear frame member 103 b . the secondary attachment 123 may have an infant car seat adapter further comprising at least one locking protrusion 127 configured to receive and engage with an infant car seat . the positioning of the locking protrusions 127 along the secondary attachment 123 may depend on the orientation and structure of the infant car seat intended for use with the secondary attachment . in one embodiment the locking protrusions 127 are biased to rotate upwards and towards the interior of the stroller to a position generally parallel to the frame of the secondary attachment 123 using spring - loaded pins or similar mechanisms . in a first position , when an infant car seat is not attached to the secondary attachment 123 , the locking protrusions 127 may be generally parallel to the frame of the secondary attachment 123 . when an infant car seat is attached to the secondary attachment 123 , the locking protrusions 127 may be pushed in a generally downwards direction until they are generally perpendicular to the frame of the secondary attachment . then the locking protrusions 127 may attach to one or more surfaces or attachment mechanisms of an infant car seat . in one embodiment , the secondary attachment 123 may have one or more sides with an elevated locking protrusion 131 , the elevated locking protrusion may be configured to engage with the back of an infant car seat . fig9 illustrates a closer view of the secondary attachment 123 engaged with the first front frame member 101 b of the stroller , as discussed in regards to fig8 . an alternatively configured secondary attachment 123 is illustrated in fig1 . the secondary attachment 123 in fig1 has two parallel portions with locking protrusions 127 , and the parallel portions are specially shaped to receive a particular infant car seat . as depicted , the secondary attachment 123 may be custom configured in any number of configurations to conform with a particular infant car seat . alternatively , the secondary attachment 123 may be configured to be compatible with multiple infant car seats . in one embodiment , the upper portion of the first front frame member 101 b may have additional attachment adapters 129 , such as receptacles , for securing the secondary attachment 123 or infant car seat to the first front frame member . fig1 illustrates the secondary attachment 123 depicted in fig1 engaged with both the first front frame member 101 b and the second rear frame member 103 b . fig1 illustrates the secondary attachment 123 engaged with the first front frame member 101 b of the stroller , as discussed in regards to fig1 . although a primary and secondary locking mechanism have been described above in view of a secondary attachment having an infant car seat adapter , it is envisioned that the primary and secondary locking mechanisms described above may also be used in connection with a basket and other secondary attachments for the stroller . in one embodiment of the stroller , the first , front and second , rear frame members of the stroller may each have double receptacles . in such an embodiment , the secondary attachment ( such as a basket ) may be stowed in a closed position using the adjacent receptacles on either frame member . additionally , the receptacles on the stroller may be interchangeable . similarly , the attachment ends of the secondary attachment may be interchangeable . in such a configuration , the secondary attachment ( such as an infant car seat adapter ) may be attached in either a forward or reverse facing configuration . fig1 illustrates handle portions 133 a and 133 b of a secondary attachment , such as a basket ( with soft portions of the basket not shown ) having attachment ends 117 , 118 engaged with receptacles 125 , 125 present on the upper portion of the second frame member 101 a and the upper portion of the first frame member 103 a , respectively . although the basket is not shown it is envisioned that the basket would extend between the rear handle 133 a and the front handle 133 b . fig1 illustrates the engagement of the front handle 133 b with the upper portion of the first front frame member 101 b via the attachment ends 118 engaging with the receptacles 125 . fig1 illustrates the engagement of the rear handle 133 a with the upper portion of the second rear frame member 103 b via the attachment ends 117 engaging with the receptacle 115 . as depicted the structural member 111 attached to the upper portion of the second rear frame member 103 b may comprise a double receptacle structure 113 with two receptacles 115 . in such an embodiment , the two handles of the secondary attachment , such as a basket , may be stored alongside each other ( as depicted in fig1 ), thus holding the secondary attachment in a stowed position . fig1 illustrates a rear top perspective view of the stroller with a secondary attachment ( basket ). illustrated are the attachment ends 117 , 118 , front receptacles 125 and rear receptacles 115 , handles 133 a and 133 b , and the like . as illustrated the basket 137 may have one or more compartments 135 . fig1 illustrates a rear view of a stroller with a secondary attachment 137 . fig1 illustrates a bottom view of the stroller with a secondary attachment 137 . fig2 illustrates a front side perspective view of a stroller with a secondary attachment 137 , such as a basket . in this view , the basket 137 is illustrated in a partially non - expanded state . fig2 illustrates the rear side perspective view of a stroller with a secondary attachment 137 in correspondence with fig2 . fig2 illustrates a top view of a stroller with a secondary attachment 137 in correspondence with fig2 . fig2 illustrates a front side perspective view of a stroller with a secondary attachment ( basket ) 137 , where the secondary attachment 137 is stowed on the second rear frame member 103 . as depicted , the attachment ends 117 of both the front handle 133 b and the rear handle 133 a of the secondary attachment 137 are engaged with receptacles 115 on the upper portion of the second rear frame member 103 b . as illustrated , in such a configuration , the receptacles 125 on the first frame member are not engaged with the secondary attachment 137 . fig2 illustrates a rear side perspective view of the stroller in the configuration discussed in regards to fig2 . in one embodiment , the base 105 of the stroller may be expandable . in such an embodiment the secondary attachment 137 may be expandable / contractible in accordance with the configuration of the base 105 . such an embodiment is depicted in fig2 . fig2 illustrates a front side perspective view of a stroller with a secondary attachment 137 , where the base 105 is expanded to a partially - expanded state . the secondary attachment 137 is also expanded in accordance with the configuration of the base 105 . in one embodiment , one or more compartments 135 , such as basket compartments , of the secondary attachment 137 may become expanded and thereby available for use by the user as the secondary attachment 137 is expanded . fig2 illustrates a rear side perspective view of a stroller with a secondary attachment 137 in correspondence with the partially - expanded state depicted in fig2 . fig2 illustrates a top view of a stroller with a secondary attachment 137 in correspondence with the partially - expanded state depicted in fig2 . a fully expanded base 105 and fully expanded secondary attachment ( basket ) 137 is illustrated in a front side perspective view ( fig2 ), rear side perspective view ( fig2 ) and top view ( fig3 ). the secondary attachment may comprise additional supports positioned between the first and second ends of the secondary attachment . although the basket example 137 is depicted herein with soft supports between the front and rear end 133 a , 133 b , the secondary attachment 137 may include rigid or semi rigid members as well . these additional supports may be configured to provide attachment points for a basket 137 such that the basket 137 may grow with the expandable stroller base 105 . additionally , the additional support members may be modular in nature and added to the secondary attachment such that the secondary attachment may adjust with the varying distance between the first , front and second , rear frame members of the stroller . in an embodiment of the stroller with a basket secondary attachment , adjustable interior panels may be utilized to create taut and usable states of the basket at different interval lengths . these interior panels may use cords , zippers , snaps and the like in order to create various basket sizes . additional attachment mechanisms may be located along the first and second frame members in order to store the secondary attachment 137 when it is not in use or provide additional support to the secondary attachment when it is in use . for example , a secondary attachment comprising a basket may include a deep basket which can attach to both the upper handles or receptacles of the stroller and the lower frame members ( including the front seat , seat support , seat recline , rear frame , etc .) using hooks , loops , snaps , velcro , and the like . additionally , the secondary attachment may comprise size - reducing elements . for example , magnets can be placed at the outer seams of the basket such that the basket is stowed is a substantially compact state . the secondary attachment comprising the basket may also include divided compartments . the basket may be divided using , for example , plastic panels located at intermediate locations . the divided compartments may aid in distributing the load move evenly across the first and second frame members of the stroller . an exemplary embodiment of the secondary attachment , in the form of a basket , is illustrated in fig3 - 44 . fig3 illustrates a front view of a basket 137 . as depicted in fig3 , a primary compartment 139 is located at a first end 141 of the basket 137 . the primary compartment 139 may be constituted of fabric panels defining a void of generally fixed length and width . in an alternative embodiment , the primary compartment 139 may be expandable or collapsible in a manner similar to the other compartments discussed below . the exterior of the primary compartment 139 comprises one or more exterior compartments 143 configured to hold goods such as keys , cellphones , wallets , credit cards , pacifiers , washcloths , and the like . the exterior compartments 143 may be netted , padded , transparent and / or opaque . the primary compartment 139 is covered with a first flap 145 configured to cover the top opening of the primary compartment 139 . in one embodiment , the first flap 145 may be magnetically attached to the exterior compartments 143 . optionally , the magnetic components may be contained within the one or more fabric layers of the flap and / or exterior compartments . alternatively , the flap 145 may attach to the exterior compartments 143 by a zipper , button , clasp , or alternative attachment means . the first end 141 of the basket 137 also comprises a handle 133 a with laterally spaced attachment ends 117 configured to attach to a frame of a stroller . in one embodiment the attachment ends 117 are substantially cylindrical and configured to be placed within one or more receptacles 125 , 113 located on an expandable stroller . additionally , rotation of the handle 133 a may cause rotation in the attachment ends 117 . fig3 illustrates a front top perspective view of the basket 137 with an open flap 145 . as depicted in fig3 , the interior of the primary compartment 139 comprises one or more interior compartments 147 configured as beverage cup holders , bottle holders , folder holders , silicone compartments , mesh / netted compartments and the like . in fig3 a top view of the basket 137 with an open flap 145 is provided such that the interior of the primary compartment 139 including the interior compartments 147 is visible . fig3 illustrates a side perspective view of the basket 137 with the closed flap 145 in a partially - expanded state . as depicted in fig3 the basket 137 comprises the primary compartment 139 and one or more expandable compartments 149 . the expandable compartments 149 may be of generally fixed width and expandable length , such that the distance between the first end 141 and second end 151 of the basket varies with the expansion / retraction of the expandable compartments 149 . the basket 137 may be partially expanded when at least one of the one or more expandable compartments 149 are partially or fully expanded . as depicted in fig3 the expandable compartment 149 a is expanded . alternatively , expandable 149 b may be expanded . either of these configurations may correspond to a stroller in a partially expanded state . the expandable compartments 149 may be located adjacent to each other such that the adjacent expandable compartments 149 share a common panel 153 . in one embodiment the panel 153 comprises double layer fabric covering an inflexible solid structure . fig3 illustrates a side view of the basket 137 with the open flap in the non - expanded state . note that the expandable compartments 149 fold substantially inwards . fig3 illustrates a side view of the partially expanded basket 137 . as depicted the expandable compartments 149 have netted side panels 161 , allowing a user to view the contents of the expandable compartment from the side . alternatively , the side panels 161 may be opaque . fig3 illustrates a side perspective view of the basket 137 with the closed flap 145 in a fully expanded state . as depicted , both expandable compartments 149 a and 149 b are fully expanded . a corresponding side view is presented in fig3 . components of the cable routing systems 155 used to expand and retract each expandable compartment 149 is visible . fig3 illustrates a top view of adjacent expandable compartments 149 of the basket 137 . as depicted , a side panel 161 facing the exterior of the basket contains a transparent mesh panel . the base 157 of the expandable compartment 149 may be gusseted 159 to allow for the expandable compartment 149 to fold substantially inwards when the expandable compartment 149 is retracted by the cable routing system 155 ( not shown ). details of the cable routing system 155 are described further below . each cable routing system 155 independently manages the expansion and retraction of each expandable compartment 149 and is depicted in fig4 and 41 . fig4 is a diagrammatic representation of the cable routing system 155 taken from a side perspective view of the basket 137 . fig4 is also a diagrammatic representation of the cable routing system 155 in a side view from the interior of an adjacent expandable compartment 149 . the cable routing system 155 comprises a top cable 163 and a lower cable 165 each comprising a first end and a second end . the first end of the top cable 167 is fixedly attached to a point 169 near the top portion of the side of the expandable compartment . the top cable 163 is routed through two holes 171 , 173 in the top portion of the side of the expandable compartment and then through at least one hole 175 facing the expandable compartment located on the common panel 153 between adjacent expandable compartments 149 . similarly , the first end of the lower cable 177 is fixedly attached to a point 179 near the bottom portion of the side of the expandable compartment . the lower cable 165 is routed through two holes 181 , 183 in the bottom portion of the side of the expandable compartment , then through at least one hole 185 facing the expandable compartment located on the common panel 153 between adjacent expandable compartments 149 . the cables 163 , 165 are each routed through at least one hole 187 also located on the common panel 153 between adjacent expandable compartments and facing the interior of the adjacent expandable compartment . once in the adjacent expandable compartment , the top and lower cables 163 , 165 are then routed through at least one toggle 189 such that the movement of the top cable is coupled to movement of the lower cable . moving the toggle in the direction substantially towards the direction of the incoming cables ( and expandable compartment ) substantially retracts the expandable compartment . moving the toggle in the direction opposite the direction of the incoming cable ( and expandable compartment ) allows expansion of the expandable compartment . additionally the second end of the top cable 191 may be attached to the second end of the lower cable 193 . alternatively , the lower cable and the top cable may comprise parts of a single cable . notably , the retraction and expansion of a single expandable compartment is independent of that of adjacent expandable compartments . a cable routing system 155 is present on both sides of each expandable compartment ; in the embodiment shown , each side of the cable routing system must be operated independently to fully expand or collapse a particular expandable compartment . the points at which the first ends of the lower cable and the top cable attach to the side of the expandable compartment may be located within the two or more layers of fabric and other material comprising the side of the expandable compartment , such that the attachment points 169 and 179 are not visible . as an alternative to the cable routing system 155 discussed herein , expansion and retraction of the expandable compartments may also be facilitated or restricted by other means , such as zippers , snaps , toggles , buttons , velcro , magnets or other known means . fig4 illustrates a top view of adjacent expandable compartments of the basket . fig4 illustrates a top perspective view of the expandable compartment of the basket 137 located near the second end 151 of the basket . similar to the first end 141 , the second end 151 of the basket 137 also comprises a handle 133 b with laterally spaced attachment ends 17 configured to attach to a frame of a stroller . fig4 illustrates a side perspective view of the basket 137 in a non - expanded state . as depicted , the basket 137 may be used as a handbag separately from the expandable stroller . fig4 illustrates a further exemplary embodiment of the secondary attachment , such as an infant car seat adapter , for a stroller system . depicted is a first frame member 201 with front receptacles 229 located within a receiving element 227 located at the top portion of the first front frame member 201 . also illustrated is the top portion of the second rear frame member 203 which may have a handle 209 . the top portion of the second rear frame member 203 may have receiving elements 211 containing rear receptacles 213 . in one embodiment , the rear receptacles 213 may be dual receptacles ( as depicted , the receiving elements 211 each contain two u - shaped openings forming the receptacles ). in an alternative embodiment , the receptacles may be semi - circular or any other open shape . a secondary attachment 221 is depicted . the secondary attachment 221 forms a generally rectangular frame with opposing first end 223 and second end 224 . the secondary attachment 221 may contain one or more locking protrusions 219 configured to engage with an infant car seat or other device to be mounted thereon . the first end 223 of the secondary attachment 221 further comprises attachment ends 225 ( each mirror images of the other ), configured to engage with the receiving element 227 . the second end 224 of the secondary attachment 221 further comprises second attachment ends 215 ( each mirror images of each the other ), configured to engage with the receiving elements 211 . the attachment ends 215 on the second end 224 of the secondary attachment 221 may include a locking mechanism with a actuator 217 operable to releasably secure the second end to the receiving elements 211 . fig4 illustrates a first state where the secondary attachment 221 is disengaged from the stroller . fig4 depicts the attachment ends 225 of the secondary attachment 221 and the front frame member 201 of the stroller in a disengaged state . as depicted , the secondary attachment 221 further comprises an attachment end 225 configured to engage with the receiving element 227 located on the first front frame member 201 . the attachment end 225 may further comprise a slot 231 adapted to receive all or a portion of the receiving element 227 therein . the slot 231 is located on the an outer surface of the attachment end 225 and is configured to substantially enclose the receiving element 227 , once engaged thereto . fig4 provides a partial cross - sectional view of the elements discussed in fig4 . the interior of the attachment end 225 may comprise a protruding attachment element 233 configured to engage a receptacle 235 , depicted here as a u - shaped receptacle , located within the receiving element 227 . the secondary attachment 221 may be attached to the stroller by way of the attachment ends 225 of the secondary attachment 221 aligning the slot 231 and protruding element 233 with the receiving element 227 located on the first front frame member 201 so that the receiving element 227 may slide into the slot 231 when the secondary attachment 221 is engaged with the stroller . when the receiving element 227 slides into the slot 231 , the u - shaped receptacle 235 may surround the protruding attachment element 233 ( fig4 - 50 further depict secondary attachment 221 partially attached to the stroller in further detail ). fig5 illustrates the secondary attachment ( infant car seat adapter ) 221 partially secured to the first front frame member 201 of the stroller . in the configuration of fig5 , the protruding element 233 has engaged in the receptacle , and the secondary attachment 221 has been rotated about the axis of the protruding element ( or in other configurations any axis formed by the attachment end of the secondary attachment 221 ), such that the second attachment ends 215 are brought closer to the rear frame member 203 and corresponding receiving elements 211 . as depicted in fig5 the receiving element 227 slides into the slot 231 of the attachment end 225 . fig5 provides a cross - sectional view of the elements discussed in fig5 . as depicted the receptacle 235 surrounds the protruding attachment element 233 . the secondary attachment 221 is then restricted from disengaging from the first front frame member 201 of the stroller by rotating the secondary attachment 221 in the direction of arrow a . receiving element 227 has a generally round outer surface , 228 and the receptacle 235 is disposed at a location spaced away from the center of receiving element , 227 . located on an inner surface of the attachment end 225 , adjacent the slot 231 is a raised portion 232 , adapted to engage the outer surface of the receiving element 227 . due to the off center location of the receptacle 235 , and therefore the axis of rotation of the secondary attachment about the receiving element 227 , as the receiving element is rotated in the direction of arrow a , the raised portion engages the outer surface 228 in a snug fit , thereby further restricting movement of the secondary attachment 221 with respect to the front frame member 201 . those skilled in the art will recognize that although this attachment mechanism is being discussed with respect to the first frame member 201 , other embodiments of the stroller may use this attachment mechanism on the second frame member 203 , as well as switching the other attachment means discussed herein between first and second frame members of the stroller . when the secondary attachment 221 is engaged with or attached to the first front frame member 201 the secondary attachment 221 is able to rotate with respect to the first front frame member 201 ( see arrow a ). to further secure the secondary attachment 221 to the stroller the second upper end 224 of the secondary attachment is rotated towards the second rear frame member 203 while the first lower end 223 of the secondary attachment is attached to the first front frame member 201 . as depicted in fig5 the secondary attachment 221 is attached to the stroller at both the first lower 223 of the secondary attachment and the second end 224 of the secondary attachment 221 . the configuration of the first lower end 223 of the secondary attachment 221 and the first front frame member 201 in such a configuration is depicted in fig5 and a cross - sectional view is presented in fig5 . as depicted in fig5 , due to rotation of the secondary attachment 221 about the axis of protruding element 233 in the direction of arrow a , the raised surface 232 located inside attachment end 225 snuggly engages outer surface 228 of the receiving element 227 . the configuration of the second end 224 of the secondary attachment 221 is illustrated in fig5 . also illustrated in fig5 is the configuration of the top portion of the second , rear , frame member 203 , which has receiving elements 211 containing rear dual receptacles 213 . the secondary attachment 221 is viewed from the interior of the secondary attachment looking outwards . similarly , the receiving element 211 is viewed from the interior of the stroller looking outwards . fig5 also depicts the elements present in fig5 ; however fig5 provides an alternative view from an opposite direction . in fig5 the secondary attachment 221 is viewed from the exterior of the infant car seat adapter 221 . the second end 224 of the secondary attachment 221 further comprises attachment ends 215 configured to engage with the receiving elements 211 . the attachment members 215 on the second end 224 of the secondary attachment 221 may include a spring loaded locking mechanism comprising an actuator 217 and a locking element 243 and protruding alignment elements 241 . fig5 provides a partial cross - sectional view of the second end 224 of the secondary attachment 221 engaging with the receiving elements 211 of the second , frame member 203 , by moving the second end 224 in the direction of arrow b . as depicted , the second end 224 of the secondary attachment 221 may align with and slide in a generally downwards direction into the receiving elements 211 , such that the dual alignment elements 241 align with the receptacles 213 ( those skilled in the art will recognize that more or less than two alignment elements and receptacles may be utilized ). the actuator 217 and locking element 243 are both shown in an expanded or non - depressed state and may be spring loaded in such a configuration . as the secondary attachment 221 engages with the second frame member 203 , by movement in the direction of arrow b , a bridge 245 between the two receptacles 213 in the receiving element 211 engages compresses the locking element 243 as the locking element 243 . the locking element 243 has a diagonal engagement surface 244 , which facilitates compression of the locking element 243 in the direction of arrow c as the locking element engages the bridge 245 . in embodiments where the locking element 243 is spring loaded in an expanded state , a spring mechanism ( not shown in fig5 , but discussed below ) within the second end 224 is compressed . the partial compression of the spring along with a compressed state of the locking element 243 is depicted in fig6 and corresponds to the partial attachment of the secondary attachment ( infant car seat adapter ) 221 with the second , rear frame member 203 . as can be seen , as the locking element 243 is compressed , the actuator 217 also moves inwardly to the second end 224 . as secondary attachment 221 moves in a generally downwards motion ( when viewed in fig6 , see arrow b ), the bridge 245 moves relatively upwards to a position between the two protruding attachment elements 241 . the central axis of the receiving element 211 contains a generally hollow aperture 247 sized just larger than the locking element 243 . as depicted in fig6 , further movement of the second end 224 with respect to the receiving element 211 will ultimately align the aperture and locking element , such that the locking element will be permitted to expand within the aperture 247 . as the locking element 243 expands within the aperture 247 , the actuator 217 also returns to its non - depressed state , placing the secondary attachment 221 into a locked state with respect to the second frame member 203 . in a locked state , the secondary attachment 221 cannot be removed from the stroller without actuation of the actuator 217 . to remove the secondary attachment 221 from the stroller , the actuator 217 may be compressed in the direction of arrow d by a user thereby forcing the locking element 243 to retract within the second end 224 , thereby disengaging the aperture 247 , so as to allow the secondary attachment 221 to be disengaged from the stroller . partial cross - sectional views of the attachment ends 215 on the second end 224 of the secondary attachment 221 are presented in fig6 - 65 . in fig6 and 63 the locking element 243 is in an expanded state . as illustrated , the locking element 243 is biased to remain in the expanded state by a spring 251 contained within a carriage 249 that is attached to locking element 243 and adapted to move therewith . the top surface of the carriage 249 has a diagonal surface ( hidden ) on which a lower end 253 of the actuator 217 , having a diagonal profile with respect to the movement of both the actuator 217 and locking element 243 rests . the interior of the locking element 243 forms a first stop surface for the spring . a stop 253 , disposed on an interior surface of the attachment end 215 forms a second stop surface for the spring 251 , thereby forming a spring seat . referring now to fig6 and 65 , when the locking element 243 is moved in the direction of arrow e , the spring 251 is compressed and the carriage 249 moves towards the interior surface of the attachment end 215 . as the carriage 249 moves , a different region of the top diagonal surface of the carriage 249 engages with the lower diagonal shaped end 253 of the actuator 217 , resulting in the movement of the actuator 217 in the direction of arrow f . applying pressure to actuator 217 to force movement of the actuator 217 in the direction of arrow f will result in corresponding movement of the locking element 243 in the direction of arrow e , thereby compressing spring 251 . likewise , when the spring 251 is permitted to expand , the locking element 243 moves back to its expanded state and the actuator 217 returns to its non - depressed state . the actuator 217 may be permitted to move in the direction of arrow f as a result of placing pressure on the locking element 243 in the direction of arrow e or engaging the diagonal engagement surface 244 with pressure sufficient pressure to force the locking element 243 to move in the direction of arrow e . it will be understood that the secondary attachments mentioned herein may have two of each of the engagement mechanisms disclosed herein , with each needing to be individually actuated or engaged , or having a single release or engagement system . although the invention has been described in terms of exemplary embodiments , it is not limited thereto . rather , the appended claims should be construed broadly to include other variants and embodiments of the invention which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention . this disclosure is intended to cover any adaptations or variations of the embodiments discussed herein .