The Nike Flex Run 2017 moves with you as you run, creating a smooth, natural feel from mile one until you're done. Breathable engineered mesh upper with supportive Flywire cables for adjustable lockdown through the laces. Soft Phylon foam inside a firm carrier unit for the perfect combination of comfort and support. Rounded heel creates a smooth transition from heelstrike to toe-off. Tri-star outsole pattern expands in all directions for a full, natural range of motion.