The collaboration between Ultra Boost and Stella McCartney brings a fresh twist to the running style of Ultra Boost with their latest Uncaged collection. Setting it apart from previous Uncaged models, the Ultra Boost Uncaged by Stella McCartney showcases a sleek design. The shoe features a Core Black Primeknit upper with seamless stitch lines that gracefully traverse the shoe's top and profile. Moreover, an appealing Eggshell Grey heel counter adds a sophisticated touch, while Stella McCartney branding is prominently placed on the heel and tongue pulls, exuding the brand's signature style. To complement the overall aesthetic, a white Boost midsole and black Continental rubber outsole are incorporated. In January 2018, the collection made its debut with three colorways: yellow, white, and the aforementioned Core Black.