For longer rides, even in the heat of summer, your sock has to serve a couple functions. One, it has to provide a smooth surface for your foot, and two, it has to wick moisture away to keep your foot dry. Castelli's Velocissimo Tour 6 Socks accomplish this by using two layers of fabric. The inner layer is Coolmax, an ultra breathable, fast wicking, and soft fabric that keeps your feet dry. The outer layer is a slightly more durable Meryl Skinlife fabric that dries quickly and is antimicrobial. No sweat, no blisters, no stink.