With an upper fabric that consists entirely of BD's Engineered Knit Technology, the Momentum provides stretch where you need it, support where it matters, and all-around exceptional breathability. Black Diamond also added a micro-fiber liner to the front of the shoe to minimize stretch and maximize comfort.The Momentum’s durable rubber is unique in that it’s molded— inspired by the way BD forges their carabiners—versus cut from one sheet of rubber. This is an engineered solution to optimize the shoe’s rubber and rands for weight, consistency, and comfort.Built for all-day comfort on moderate routes, boulders, or gym sessions, the Momentum features a soft flex midsole for sensitivity and is the perfect entry level climbing shoe. And just to stress this, if you climb in hot or humid climates, this is just about the most breathable climbing shoe on the market.