VISIBLE WEATHER PROTECTION. PREMIUM STABILITY. The Nike Air Zoom Structure 18 Flash (2014 Chicago Marathon) Women's Running Shoe features firmer foam for increased stability and ultra-responsive, high-speed cushioning to go faster, longer. The upper offers excellent visibility and weather protection to help you run in wet and dark conditions. Graphic details pay tribute to a world-famous foot race by the lake. Increased Stability The Nike Air Zoom Structure 18 improves upon its predecessor with a triple-density Dynamic Support midsole. A new firmer foam along the heel and medial midfoot helps reduce excessive pronation, while Dynamic Support technology uses lightweight wedged foam to support your foot, dramatically increasing stability without adding weight. Weather Protection and Visibility The engineered mesh upper repels water to help keep feet dry while providing superior support and ventilation. Allover reflectivity enhances visibility in low light. Responsive Cushioning Nike Zoom Air cushioning in the forefoot delivers a crisp, quick ride. Embedded in the Zoom Air bag are tiny fibers that flex into power position on impact, launching your step and setting up your next one. The result: pure, explosive, unrelenting speed. More Benefits Internal toe tip for structure and durability Full mesh inner sleeve for enhanced breathability and a sock-like fit Compression-molded Phylon and Cushlon foams fused together for lightweight cushioning Rubber crash rail on lateral outsole for soft, smooth transitions Deep flex grooves for a smooth, efficient stride Internal heel counter for a snug, secure fit