Built for your fastest half- and full marathons, the Cloudboom Strike revolutionizes the racing experience. Ultra-responsive Heliona" HF hyper foam and an innovative drop-in midsole - which we call a Bounceboard - propel you forward with power. Design: Ultralight and breathable, the one-piece, semi-transparent mesh upper helps to reduce overheating The cage-like construction locks down the midfoot for a secure, race-ready fit In-Shoe Comfort: Functioning like a drop-in midsole, the innovative Bounceboard boosts the shoe's stack height for maximum energy return - all while abiding by stack height regulations Strategically-placed CloudTecA(R) elements create a faster, smoother roll-through, while the ultra-cushioned ride protects against impact Made with stiff carbon fiber, the spoon- shaped SpeedboardA(R) works like a spring, absorbing energy and transferring it into the forefoot for the most powerful take-offs possible Additional Details: Best for: Running, Marathon, Road running, Competition Weight: 7.4 oz / 210 g Heel-to-toe Drop: 4 mm