The leading shoe for 2015 in the adidas Boost collection, the Ultra Boost comes with a full-length energy-returning boostâ„¢ midsole that keeps every step charged with an endless supply of light fast energy.The Ultra Boost has a Primeknit upper that delivers a precision fit with a seamless, single-piece textile upper, while TORSION® SYSTEM support offers midfoot integrity and energised transition and a Stretch Web outsole offers ultimate durability. A newly designed heel counter offers optimum heel hug.Three years in the making, Primeknit was first introduced at the London 2012 Olympic Games and consists of a revolutionary and sustainable digital engineering process that results in a seamless, one-piece knitted upper from fused yarn. Primeknit not only offers superior comfort, it also fine-tunes flexibility and support, providing strength in every direction.