Nike Men's Free Trainer 5.0 Tb Ankle-High Tennis Shoe synthetic-and-mesh Synthetic sole Shaft measures approximately 3" from arch Woven upper made from lightweight nanoply provides a snug fit. Dual-density midsole offers lightweight, plush support. Flex grooves help promote natural range of motion. DiamondFLX design enhances multidirectional flexibility. Triangular-shaped nodes in the outsole provide excellent grip.