Made for the best and those who aspire to be, the GP Challenge 1 helps you serve and swing with confidence. With Air Zoom units and side-to-side stability, it's made to unleash your inner might and smash whatever comes your way when it's match point. Zoom, Zoom A forefoot Air Zoom unit helps you play on your toes and puts a pop in your first step. A heel Air Zoom unit provides support. Stay in Motion A strong midfoot plastic plate adds stability for quick cuts and power to your game when transferring energy from motion to motion. Webbing around the eyestays combined with the plate offer a sort of "hugged" containment when moving side-to-side. The heel is extra padded to help keep you comfortable and supported.