The On Cloudboom Strike gives you marathon-tailored comfort and record-breaking speed. This race-day shoe is a game changer. Its innovative Bounceboard cushioning works like a drop-in midsole by boosting the shoe’s stack height for maximum energy return. Throw in a stiff, full-length carbon-fiber Speedboard on top of Helion™ HF hyper foam, and you’ve got a seriously fast and lightweight ride to propel you forward. Details: Upper: Ultralight and breathable, the one-piece, semi-transparent mesh upper helps to reduce overheating. The cage-like construction locks down your midfoot for a secure, race-ready fit. Midsole: Engineered with Helion HF™ hyper foam, the ultra-cushioned midsole and removable Bounceboard construction provide maximum energy return, cushioning and impact absorption—all while abiding by stack height regulations. A spoon-shaped carbon fiber Speedboard works like a spring, absorbing energy and transferring it into the forefoot to give you powerful toe-offs. Outsole: A rubber outsole with strategically placed CloudTec® elements creates a faster, smoother roll-through.