NIKE Free Run+ 2 Men's Running Shoes Inner sleeve - For a snug fit and to move with the natural motion of the foot as well as to enhanced breathability keeping your feet comfortable. Bonded synthetic overlays - These lightweight and flexible thin strip are attatched to the mesh upper for a streamlined fit, provides a super-strong and flexible support. Fused Phylite Midsole and outsole - This ultra-lightweight material provide an extremely smooth and resilient ride giving you a comfortable running experience. Deep flex grooves - Located along the outsole for natural range of motion and flexibility. "Centre of Pressure" design - Located at heel, this provides additional cushioning on contact, maximising overall flexibility.