Ryka Women's Optimum Mary Jane 2 100% Mesh and synthetic Rubber sole Synthetic leather, mesh and high density foam upper Removable Nitracel footbed with EVA strobe board Lightweight molded EVA midsole with Nitracel forefoot pad Nitracel Cushioning Cartridge for energy return. Engineered from Nitrogen-infused foam, this innovative heel cushioning cartridge absorbs impact and provides energy return for a smooth, resilient ride Five-piece, solid rubber outsole with balanced flex grooves offer the perfect balance between traction and flexibility