Prototype after prototype. Innovation after innovation. Testing after testing. Meet us in the hot pursuit of the pinnacle harmonization of weight, cushioning, and responsiveness. Ultraboost 21. Say hello to incredible energy return. Sock-like fit Lace closure adidas Primeknit+ textile upper Boost midsole Textile lining Weight: 10.9 ounces Midsole drop: 10 mm (heel: 24.2 mm / forefoot: 14.2 mm) Continental™ Rubber outsole Primeblue Men's Adidas Ultraboost 21