Nike Flex Trainer 2 - Women's The Nike Flex Trainer 2 is a supportive, lightweight, flexible shoe for multi-directional training. Synthetic leather and mesh upper with midfoot fit system and internal half innersleeve provides optimal lockdown for low-to-ground training. Injected unit sole Phylon™ in the midsole adds lightweight cushion. Slight midsole wrap-up on forefoot enhances support and traction. Solid rubber pods on the heel, toe and forefoot give traction. Flex groves on the outsole create flexibility and allow foot to move in natural motion.