The adidas UltraBoost 21 ‘Solar Yellow’ combines eye-catching style with lightweight and responsive performance. A fluorescent monochromatic finish is applied to a sock-like Primeknit upper that incorporates Parley Ocean Plastic and other recycled materials. Full-length Boost cushioning is supported by a Continental rubber outsole and a revised Torsion system dubbed Linear Energy Push, good for increased forefoot stiffness and enhanced energy return.