We love our big, 6" cuff designs for many reasons. For one, they offer a nice, big palate for artwork. The Cosmo is a treat for the senses. The Aireator is the original airflow design that changed how modern endurance socks are made. With its trademark venting mesh weave foot, durable 6" StayFast cuff, and durable heel and toe, the Aireator guarantees long-lasting performance. Made with CoolMax(R) EcoMade?, from recycled resources. Composition: 60% Nylon, 39% COOLMAX EcoMade, 1% Lycra. Sizing: Small (Women 6-8); Medium (Men 7-9 / Women 8.5-10.5); Large (Men 9.5-11.5 / Women 11-13); Extra-Large (Men 12+).