The adidas Ultra Boost 4.0 ‘Grey’ launched in November 2017. A light grey shade is used throughout the shoe’s performance build, spanning the midfoot cage, molded heel stabilizer and Primeknit upper. The latter shows off the ribbed construction specific to the Ultra Boost 4.0, with varying knits on the toe and collar contributing to the adaptive fit of the Primeknit build. White Boost cushioning underfoot is reinforced with a black Stretchweb outsole.