Nike Men's Flex 2017 RN Running Shoes Top to bottom, the Nike Flex 2017 RN Running Shoe is built to flex. Its one-piece engineered mesh upper, adaptive heel design and molded tri-star outsole pattern work together for a smooth ride that moves with your stride. Dynamic Flywire cables provide a 1:1 fit Engineered mesh provides breathable support Tri-star outsole pattern enhances flexibility Minimal heel design provides a more natural fit Co-molded midsole uses a softer injected Phylon (