UPPER: Welded TPU mesh with dynamic Flywire technology for secure fit and protection. MIDSOLE: Low-profile Phylon midsole for lightweight, responsive cushioning. Sidewall wrap-up design cradles the heel and the midfoot. OUTSOLE: Delta nodes traction pattern provides ultimate grip on multiple surfaces. DiamondFLX design aid multi-directional movement. The lightest, lowest free trainer in the industry.