Heavy duty, fast-drying merino wool sock specifically designed for cold or winter climates. Heavy cushion surrounds entire foot and leg, reinforced heel and toe, ankle and arch support. 37.5 active particles supercharge wool's natural abilities by attracting moisture while still in vapor form, before it becomes a sweat droplet. Stay drier longer and increase athletic output. Wool 79% Spandex 3% Nylon 18%