Castelli claims the best sock they've ever made for performance cycling is the Rosso Corsa Pro 15 Sock. And, they might be right. It's constructed from multiple-structure knit with extra stretch and a compressive midfoot support band. An asymmetrical construction mirrors the shape of the foot, and Meryl Skinlife yarns with anti-odor silver ions reduce odor. A cushioning pad under the ball of the foot adds comfort, and there's even a reflective tab at the back.