a serrate surface see fig1 any conventional adhesive may be applied to the peripheral margins 90 of exposed layer 20 and bottom plate 40 to provide means to secure the two layer members to each other the flex plate 30 is freely suspended between exposed layer 20 and bottom plate 40 flex plate 30 may be attached to bottom plate 40 at the heel portion 80 by way of adhesive similar to that used on the peripheral margins 90 or by other suitable connecting means while the flex plate bottom surface 32 rests on the bottom plate top surface 41 it should be noted that the two surfaces 32 and 41 are not in constant contact referring to fig3 a small cavity 50 is formed between surfaces 32 and 41 when the sole liner rests in a neutral position with no force exerted on exposed layer 20 the cavity 50 is in constant flux during striding as illustrated in fig4 and 5 referring to fig4 when the heel of a foot not shown exerts force 60 on the heel portion 80 of sole liner 10 the cavity 50 is displaced toward the toe end 70 of the sole liner 10 as seen.