NIKE Women's Air Zoom Structure 18 Running Shoe Synthetic Lightweight engineered mesh upper with strategically placed bonded overlays for added support Co-molded, dual-density foam in the midsole with forefoot Nike Zoom unit Environmentally preferred rubber Waffle outsole with BRS 1000 in the heel for durability Medial adaptive fit system wraps the arch Decoupled crash pad for a smooth, supportive ride