Inov-8 Men's F-lite 250 Cross-trainer Shoe 100% Synthetic Imported Synthetic sole Functional fitness workouts, CrossFit, weightlifting, running. The Powerheel is 40% denser than the forefoot of the shoe and with a 8mm heel-toe differential, the Powerheel provides maximum power and mechanical advantage when lifting weights. The midfoot lockdown holds your foot secure to the sole ensuring the shoe will move fast with your every step. Next generation Meta-flex technology and optimal multi-directional flexibility moves with the foot forward or laterally. 360 degree Rope-tec system extended onto the shoe's upper delivers traction and durability on rope climbs.