The adidas UltraBoost 21 'Grey' showcases a sleek and versatile design that enhances both performance and comfort. This performance running shoe boasts a monochromatic neutral colorway, offering a modern and understated look. Crafted with a breathable knit upper, it not only ensures optimal ventilation but also promotes sustainability thanks to its incorporation of recycled Primeblue materials, including Parley Ocean Plastic. The shoe's remarkable cushioning system is powered by full-length Boost technology, delivering exceptional responsiveness and support. In contrast to its predecessor, the UltraBoost 20, the UltraBoost 21 houses 6% more Boost capsules, elevating its energy return capabilities. Enhancing the shoe's overall performance, a revised Torsion system named Linear Energy Push enhances forefoot stiffness and maximizes energy return for an enhanced running experience.