The adidas UltraBoost 21 "Grey Screaming Orange" features sharply contrasting hues on the sock-like Primeknit upper. The two-tone knit construction is reinforced with a semi-translucent midfoot cage and a molded heel counter in a gradient purple and orange finish. The lightweight build is mounted on a full-length Boost midsole, shaped with an exaggerated heel curve and enhanced with Linear Energy Push, a revised Torsion system designed to yield a more responsive ride.