The absolute ultimate in warmth and comfort with super versatility combined with super soft texture. High ribbed cuffs extend to mid-calf. The gathered band at center foot holds sock in place. Thick to the touch but yet air light and breathable. Inside resembles silky terry cloth that naturally wicks away perspiration. The Ultimate Outdoor Sock retains super warmth even when wet and is incredibly durable unlike the Smart Wool products. 42% alpaca/32% acrylic/18% nylon/3% lycra /5%Spandex.