in the following detailed description , reference is made to the accompanying drawings , which form a part hereof . in the drawings , similar symbols typically identify similar components , unless context dictates otherwise . the illustrative embodiments described in the detailed description , drawings , and claims are not meant to be limiting . other embodiments may be used , and other changes may be made , without departing from the spirit or scope of the subject matter presented here . it will be readily understood that the aspects of the present disclosure , as generally described herein , and illustrated in the figures , may be arranged , substituted , combined , and designed in a wide variety of different configurations , all of which are explicitly contemplated and make part of this disclosure . the present disclosure pertains , inter alia , to a step apparatus with variable height step platforms , with height settings which can be changed quickly , and without the necessity of additional pieces that may be dangerous in an exercise class situation . fig1 shows an exemplary embodiment of the step apparatus 001 , in a first position with two platform units 100 a and 100 b fitted and seated inside the frame 010 . as shown in fig2 , the frame 010 has vertical inner side walls 020 , and a lip , or a ledge 015 extending from the vertical side walls 020 within the frame 010 . the ledge 015 supports flippable step platform units 100 a and 100 b . it is not necessary that the ledge 015 extend completely along inner periphery of the frame ( e . g ., it can be broken up into multiple sections or segments ). the step platform unit 100 includes primary box 105 which has a length and width sized to rest on the frame ledge 015 so that the units 100 are supported within the frame 010 . this box 105 may simply provide a platform and the seats for the ledge , without being a “ box ”— its height corresponds to the distance from the ledge 015 to the top of the frame 010 , and may simply be one rigid sheet . the top surface 022 of box 105 provides a flat step platform , and its length and width is sized to be supported by the ledge 015 within the frame 010 . in this position , the flippable step platform unit 100 provides a step platform surface 022 of box 105 , at a step height flush to the top of the frame 010 . as shown in fig1 and fig2 , the frame 010 has outer walls 016 , and may also have legs 014 ; however , legs 014 are not required for this invention to work properly . the frame 010 need not have solid walls 016 throughout , and may have only connectors or a partial wall 017 on some sides . the frame 010 may have rounded sides 012 for a safer , more aesthetic step . these features may be incorporated as long as they do not hinder the functions of the steps . as shown in fig1 and fig2 , a separator wall 011 may separate the two platform units 100 a and 100 b , and help stabilize the step platform units 100 against the frame 010 . the separator wall 011 also has the ledge 015 running along the inside , allowing for unbroken support ledges 015 along the inside of the frame 010 , and providing extra support spanning across the length of the stepper apparatus 001 . fig3 shows two flippable platform units 100 a and 100 b within the step frame 010 , both flipped to the second setting , with the second boxes 106 a and 106 b in the upward facing in - use position . in this flipped position , the second boxes 106 a and 106 b provide step platform surfaces 024 that are elevated above the frame . when a frame - height step is desired , box 105 faces up and is situated over box 106 , which is within the frame . when the unit 100 is flipped so that box 105 is under box 106 , the platform 106 rises above the step frame 010 and provides an alternate height step in the step apparatus 001 . in this flipped orientation , the first box 105 is still the box seated on the ledge 015 ( just flipped over ). fig4 shows one step platform unit 100 a with box 105 flipped up to be used as a step platform 022 at the frame height , and a second step platform 100 b with step box 106 flipped up to be used as a platform 024 at an elevated height above the frame height . in this configuration , a step exercise may be performed at two heights , for two intensities . fig5 shows both flippable step units 100 a and 100 b in frame 010 flipped to the second position . unit 100 a has second step platform box 107 and unit 100 b has second step platform box 106 , both of which have different heights . fig6 shows an alternate embodiment of the step apparatus 002 with a first flippable step platform 200 a in the first position with box 205 facing up , and the second flippable step platform unit 200 b in the alternate position , with box 206 facing up as the usable step platform . in this embodiment , the box 206 includes a triangular vertical cross section to provide a tilted or sloped exercise platform surface 250 ( see fig7 ). in fig6 , the frame 210 with walls 216 is slightly shorter than the frame 010 in fig1 - 5 , and has access ports 225 to easily access the flippable step platform unit 200 to remove or flip ( see , also , fig8 ). however , the sloped step 200 , the lower frame 210 , and the access ports 225 can be implemented independently . rubber feet 220 which extend through the frame 210 can be seen at intermittent points along the base , or frame 210 . the ledge 215 operates the same way as with other configurations . fig7 shows the step platform box 100 with box 108 in detail . the tilted step surface 250 may be covered with a non - skid rubber and / or a non - skid pattern 251 . fig8 shows a user removing and replacing a step unit on a two unit step apparatus . the user sets flippable step unit 200 a on inner ledge 215 for use . the user accesses flippable step unit 200 b through access port 225 to remove the step unit 200 b . fig9 shows an enlarged view of one side of the step apparatus 002 with an attached accessory 500 looped through attachment points 230 on frame 210 . examples of accessories include exercise bands , tubing , and cable . examples of attachment points include one or more loops , hooks , posts , snaps , buckles , velcro ® and the like . the entire step apparatus 001 may be made of a durable plastic and can be made by injection molding , or from molded pieces . rubber pieces 020 may be added to the bottom of the stepper frame to reduce friction , so it does not slip during use . the embodiments in this disclosure are exemplary and should not be taken to be limiting . any number of steps can be included . the frame and boxes can be made in any size or shape , and with any material which can perform equivalent to the apparatus of this disclosure . this step apparatus may be used for individual training or group fitness classes . the stepper could be used by way of body weight or weighted resistance . the user may use a plurality of step heights in one unit for a dynamic work out . the step heights may also be adjusted to user preference .