Abstract: An elongated perimeter outlining a substantially planar foresole region, a substantially planar heel region, and an arch region recessed from the foresole and heel regions, each of the regions having medial and lateral sides; a heel pad attached to the heel region; a plurality of pockets formed in the foresole region, each pocket having a base and a rigid rim rising from the base above the plane of the foresole region; and a slide pad element in each pocket, having a bottom surface interchangeably secured to the base of the pocket and an outer slide surface, and a peripheral edge which closely conforms to the rim, wherein the conforming edge has a bottom edge portion substantially abutting the rim, and an upper edge portion that protrudes above the rim, whereby the rim is recessed relative to the slide surface.