The Fox River Extra Heavy Weight Over-the-calf Outdoorsox Sock Style # 7267 is made of premium pre-shrunk worsted wool that keeps feet warm and wicks moisture naturally. Wool is a superior natural insulator. Super power ribbed leg stimulates circulation and prevents muscle fatigue. Thermalined foot for shock absorption and insulation. Has smooth, flat toe seam. 84% wool, 9% acrylic, 7% nylon.