Engineered mesh upper for ventilation and support. Reflective midfoot saddle with no-sew overlays to lock down the foot for support and comfort. Reflective skin under the saddle for enhanced visibility in low-light conditions. Nike Zoom unit in heel for low-profile, responsive cushioning. Natural motion design reduces overlays in flex zones so your foot can move freely. Environmentally preferred rubber Waffle outsole for multisurface traction and durability. Weight: 8.8 ounces (women's size 8) Cushlon foam for soft, springy and responsive cushioning and a supportive feel. Deep flex grooves at heel for impact dampening and flexibility. Rubber blades on lateral outsole for a soft, smooth transition. Nike+ ready.