Nike Men's Free 5.0+ Breathe Running Black / Metallic Dark Grey / White Synthetic Shoe - 7.5 D(M) US Synthetic-And-Mesh Rubber sole Textured mesh full inner sleeve for a dynamic, sock-like fit and easy on and off Asymmetrical lacing system for reduced pressure on the top ridge of the foot Diagonal cuts through the arch to encourage natural motion and help increase foot strength