Avia - A00660 (White/Crystal Blue/Submarine) - Women's: The Cantilever(R) centers the heel over a concave sole. The concave sole acts like a trampoline to soften impact, stabilize the heel and provide increased energy return. Water drainage system for water fitness activities. Synthetic and lycra/neoprene upper with hook-and-loop fastener. Removable molded EVA sockliner. Compression molded EVA midsole. Non-slip sticky rubber outsole.