The Wooleator is a very thin, flat-knit wool sock with a StayFast cuff and Aireator mesh weave across the entire top of the foot for comfort and breathability. Flat-knit, Stay-fast Cuff Machine wash cold, tumble-dry low, no chlorine bleach Materials: 62% Merino Wool, 23% Nylon, 15% Lycra Aireator mesh weave