NIKE Air Zoom Structure Triax+ 15 Breathe Running Shoes Lightweight breathable open sandwich mesh upper - keeps your feet cool whilst our running in hot conditions. Phylon midsole - A responsive, cushioned EVA midsole material keeping you from landing too heavy and makes your ride much more comfortable. Dual density - Higher density EVA on the medial (inside) of the shoe which helps prevent over pronation and keeps your feet in an upright position. Dynamic Archbridge - TPU (plastic) bridge that sits next to the dual density and acts as an additional feature to reduce over pronation. TPU overlays - Supportive overlays lock your foot in place and stops it from slipping about reducing the risk of blisters and injuries.