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 has extra padding to help keep you comfortable and supported. Durable Traction Extra rubber in the toe area, specifically the big-toe side, adds durability. High-abrasion rubber in the forefoot offers durability and traction. We designed the heel specifically for rocker-like movements, like pulling back for a serve.