Caring for the environment never looked (or felt) so good. Support your fitness goals while you support the planet with the adidas by Stella McCartney Ultraboost 21, the latest incarnation of our most famous running silhouette that was designed and tested for 10km runs. The shoes are the perfect mix of style and functionality, with nods to both Stella McCartney's powerful visual identity (here's looking at you, metallic upper) and adidas' performance-first approach to design.