The Aetrex X521 High Performance Runner is made from technologically advanced leathers, polyurethanes, and moisture transferring polyesters to keep the foot in a healthy, cool environment. The biomechanically engineered, multi-density midsole features a Carboplast foot bridge for motion control and stability. Special features include an Airlex 2 way open air sandwich mesh upper and a high, wide toe box for forefoot comfort. Available in three widths, Medium (B,C), Wide (D,E), Extra Wide (EE, 3E).