fig5 the slot 20 preferably is at the top of the cavity 14 located around the periphery of the cavity 14 are a plurality of flaps 22 the bottoms of the flaps are contiguous with the bottom surface 18 of the sidewall and they have a thickness b fig4 which is less than the thickness a in the embodiment illustrated the flaps are located in pairs with one flap in each pair being on each side of the shoe one pair of flaps 22 is located around where the ball of the user 39 s foot would be one pair is located around where the arch of the user 39 s foot would be and another pair is located around where the user 39 s heel would be the sidewall 18 includes a passageway 24 at its back edge which extends between the cavity 14 and the back of the shoe a sole plate 26 is sized to fit within and substantially fill the cavity 14 the sole plate has generally the same thickness as the thickness of the sidewall however due to the tread pattern located on the bottom surface 27 of the sole plate its thickness varies in any event the bottom surface of the sole plate is generally flush with the bottom surface 18 of the sidewall 16 in order to provide a stable bottom on the shoe the sole plate is made from an elastomeric material and preferably has a flexibility that is similar to that of the sole 12 a thin tab 28 located at the toe end of the sole plate fits into the slot 20 when the sole plate is inserted into the cavity in the embodiment illustrated the tab is an extension of a thin base layer 30 which forms the.