The adidas UltraBoost 21 ‘Halo Silver’ treats the lightweight running shoe to a subdued greyscale makeover, one that allows the sneaker’s performance capabilities to claim the spotlight. They include a reconfigured Boost midsole that packs 6% more Boost capsules than the shoe’s predecessor, along with a revised Torsion system that increases forefoot rigidity to deliver a more responsive run. Up top, the knit upper continues adidas’ sustainability efforts with the inclusion of Parley Ocean Plastic and other recycled high-performance materials. In good pre-owned condition.