Help achieve a personal best with the Y-3 Ultraboost 5 runners. With a signature PRIMEKNIT upper, an all new TPU heel cage elevates the design. Featuring a BOOST midsole for lightweight cushioning and performance, a Continentalâ„¢ Rubber outsole provides traction with every step. PRIMEKNIT Upper, Lace Closure, TPU Heel Cage, BOOST Midsole, Continentalâ„¢ Rubber Outsole, Y-3.