Ryka Women's Optimum Mary Jane is a crossover combining the comfort and stabiity of a walking shoe witht the styling of a traditional mary jane. 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. Solid rubber outsole with balanced flex grooves offer the perfect balance between traction and flexibility.