the present invention may be understood more readily by reference to the following detailed description taken in connection with the accompanying drawing figures , which form a part of this disclosure . it is to be understood that this invention is not limited to the specific devices , methods , conditions or parameters described and / or shown herein , and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the claimed invention . any and all patents and other publications identified in this specification are incorporated by reference as though fully set forth herein . also , as used in the specification including the appended claims , the singular forms “ a ,” “ an ,” and “ the ” include the plural , and reference to a particular numerical value includes at least that particular value , unless the context clearly dictates otherwise . ranges may be expressed herein as from “ about ” or “ approximately ” one particular value and / or to “ about ” or “ approximately ” another particular value . when such a range is expressed , another embodiment includes from the one particular value and / or to the other particular value . similarly , when values are expressed as approximations , by use of the antecedent “ about ,” it will be understood that the particular value forms another embodiment . turning now to the drawings , fig1 - 22 depict a preferred embodiment of an interchangeable putter grip system , generally referenced as 10 , in accordance with the present invention . grip system 10 is illustrated as being installed on a typical golf putter , generally referenced as 1 , which includes a putter head 2 and a shaft 3 . fig2 and 2a provide a detailed view of grip system 10 installed on putter 1 , and particularly reveal the outer sleeve member , generally referenced as 30 , including a main body 31 , a bottom cover 32 and a top cover 33 . fig1 depicts grip material 36 ( shown in partial view ) disposed on main body 30 . grip material 36 may comprise any suitable material such as such as leather , rubberized material , or natural or synthetic grip material . grip material may comprise the form of a wrap , a sleeve , or any other suitable structure . fig3 and 4 provide exploded illustrations of the interchangeable putter grip system 10 in accordance with the present invention . a butt end of the putter shaft 3 receives a suitable number of wraps of grip tape 4 to build up the outer diameter of the putter shaft to a sufficient degree to receive an inner sleeve , generally referenced as 20 inserted thereon . grip tape 4 may comprise double sided tape , solvent activated golf grip tape , or any other suitable adhesive material or substance . inner sleeve 20 is then slidably installed onto the butt end of the shaft 3 so as to become generally permanently affixed to the putter shaft . it should be noted , however , that inner sleeve 20 may be removed and transferred to another putter shaft if desired . once inner sleeve 20 is installed , outer sleeve 30 is installed by receiving inner sleeve 20 concentrically disposed therein . a screw - in weight 40 is axially inserted through the top end of outer sleeve 30 and placed in threaded engagement with a threaded aperture formed in the top end thereof thereby fixing the outer sleeve 30 relative to the inner sleeve 20 . with reference to fig5 - 8 , there are provided detailed illustrations of inner sleeve 20 . inner sleeve 20 comprises a generally tubular structure which is preferably fabricated from suitable injection molded plastic , however , any suitable material may be used . inner sleeve 20 includes a generally tubular main sleeve body 21 having a generally open bottom end 22 and a top end 23 . main body 22 defines a shaft receiving inner chamber bounded by an inner surface . a plurality of longitudinal radially inwardly projecting ribs 24 extend from said inner surface . ribs 24 function as inner sleeve 20 is slid over the putter shaft to locally displace or dig into the grip tape 4 thereby anchoring sleeve 20 relative to putter shaft 3 . it should be noted at this juncture that inner sleeve 20 may function as a golf putter grip without use of outer sleeve 30 . bottom end 22 includes a radially enlarged collar 25 defining a recessed groove 26 which includes a longitudinal inlet 26 a , a circumferential extension 26 b extending from inlet 26 a , and a bayonet detent 26 c which functions to lock in outer sleeve 30 as more fully discussed herein . collar 25 may be integrally formed with sleeve 20 , or alternately formed by affixation of a separate annular member . the top end 23 of inner sleeve 20 includes an axially disposed centering projection or bumper 27 which functions to ensure that , upon installation , outer sleeve 30 is concentrically disposed about inner sleeve 20 . fig9 - 12 provide various detailed illustrations of outer sleeve 30 which functions as the grip . outer sleeve 30 comprises a generally tubular rigid structure which is preferably fabricated from suitable injection molded plastic ; however , any suitable material may be used . outer sleeve 30 further includes a bottom end cap 32 and a top end cap 33 . end caps 32 and 33 are preferably separate attachable members , however , forming end caps 32 and 33 integrally with outer sleeve 30 . at least outer sleeve 30 , and preferably bottom cap 32 and top cap 33 , define an irregular outer surface which allows for an enhanced ergonomic putting grip . with reference to the end view of top cap 33 as seen in fig9 , the irregular outer surfaces include an arcuate rear segment 33 a , a generally planar front segment 33 b with planar lateral segments , each referenced 33 c , connecting the front and rear segments . the outer surface 31 of outer sleeve 30 has corresponding segments as best illustrated in fig1 wherein actuate rear surface segment 31 a , planar top surface segment 31 b , and one of the planar lateral segments 31 c are seen . bottom end cap 32 conceals a bayonet pin ring 34 having a pair of bayonet pins 35 projecting radially inward therefrom . bayonet pins 35 are received within recessed groove 26 on inner sleeve 20 and function to retain outer sleeve 30 relative to inner sleeve 20 . top end cap 33 defines an internally threaded aperture 36 for receiving an externally threaded weight 40 as more fully discussed below . finally , the interior of sleeve 30 defines a chamber for receiving the inner sleeve inserted therein , and a plurality of longitudinal radially inwardly projecting ribs 38 project from the inner surface of sleeve 30 . ribs 38 function to engage the outer surface of inner sleeve 20 to align and center the outer sleeve upon installation . fig1 a - 13e illustrate mating engagement of outer sleeve 30 with inner sleeve 20 with the putter shaft omitted for the purpose of this illustration . outer sleeve 30 is positioned to slide onto inner sleeve 20 as illustrated in fig1 a . next , outer sleeve 30 is slidably installed concentric , axially aligned relation with inner sleeve 20 as illustrated in fig1 , whereby bayonet pins 34 are received within bayonet groove 26 through inlet 26 a . a small axial force is applied such that bayonet pins 35 reach the end of grove inlet 26 a at circumferential groove extension 26 b . as illustrated in fig1 c , the outer sleeve is then rotated approximately a quarter - turn whereby bayonet pins 35 travel along circumferential groove extension 26 b to detent 26 c . next a screw 40 ( which may be weighted ) is inserted within internally threaded aperture 36 in top end cap 33 and tightened using a hand tool 50 thereby ensuring that the outer sleeve assembly is precisely centered relative to inner sleeve 20 and fixed relative thereto . as best illustrated in fig1 and 15 a - 15 e , the interchangeable grip assembly of the present invention allows the user to quickly and easily install various grips . fig1 illustrates a putter having grips of varying sizes , namely small 30 s , medium 30 m , large 30 l , x - large 30 xl , and xx - large 30 xxl . as noted above , the grips may be adapted with logos or other indicia molded , stamped , printed , or embossed on or into the grip material . fig1 a - 15e provide further illustrations of various grip sizes with end views illustrating the screw - in weights , referenced as 40 a - 40 e . weights 40 a - 40 e may vary in mass as further discussed below thereby allowing the user to add or subtract weight from the putter . each weight 40 defines an axial keyed recess which receives the mating end of tool 50 . fig1 - 21 illustrate a hand tool , generally referenced as 50 , for use in installing and removing outer sleeve 30 from inner sleeve 20 in accordance with the present invention . hand tool 50 includes a generally t - shaped main body 52 having an upper portion 53 and a lower portion 54 . main body 52 defines a generally inverted l - shaped through bore 55 which terminates at an axial opening in the bottom of main body 52 . through bore 55 receives a generally l - shaped wrench 56 having an end defining a male torx ® head . torx ® is a trademark for a type of screw head characterized by a 6 - point star pattern . in addition , both opposing ends of wrench 56 may be adapted with the torx ® head . wrench 56 is employed in installing and removing screw - in weights 40 , which are each also adapted with a female torx ® head . while the preferred embodiment of the present invention , and particularly wrench 56 and screw - in weights 40 are disclosed as incorporating the torx technology , any suitable threaded fastener and wrench configuration are considered within the scope of the present invention . a magnet 57 is affixed to main body 52 within aperture 55 and functions to maintain wrench 56 removably magnetically attached thereto . the main body 52 of tool 50 is further adapted with female threaded apertures which function to removably receive a screw - in weights 40 as best illustrated in fig1 - 21 . by simply removing wrench 56 from main body 50 , the user is able to remove one of the four screen - in weights stored on the tool body to alter the weight of the putter as illustrated in fig2 . as noted above , weights 40 a 40 e are provided with varying mass including a weight increments that range from a 0 - gram screw in weight 40 a , 5 - gram screw - in weight 40 b , 10 - gram screw - in weight 40 c , 15 - gram screw in weight 40 d , and a 20 - gram screw - in weight 40 e . each weight preferably includes an indicator that informs the user exactly how much the weight weighs . while the present invention has been disclosed in its preferred embodiment as an interchangeable grip system for golf putters , the advances discloses herein may be adapted for use on other golf clubs , such as irons , metal woods , and drivers . in addition , the system interchangeable grip system herein may further be adapted for use with a wide variety of goods having grips , including without limitation , billiard / pool cue sticks , lacrosse sticks , tennis racquets , etc . finally , the interchangeable grip system is further suitable for use with non - sports related goods , such as umbrellas . the instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment . it is recognized , however , that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art .