The adidas UltraBoost 21 Cold.Rdy 'Halo Silver Ice Purple' gives the performance running shoe a winter-ready makeover. Made in part with Parley Ocean Plastic, the insulated, water-resistant upper features black Primeknit construction with grey synthetic overlays. The neutral color scheme is enlivened by a purple-tinged heel counter and a webbing pull tab in mint green. Responsive cushioning arrives via a full-length Boost midsole, supported by a Continental WinterGrip Rubber outsole.