Nylon. Lightweight ski sock with moisture wick technology. Shin and sole are cushioned for shock absorbtion. Memory knit and contoured rip top to stop slippage. Easy to clean and machine washable. Composed with polyester, nylon and spandex The Mammoth sock from Fox River is insanely comfy, warm and will keep your feet dry as a bone inside your boots. These are a medium weight sock with added cushioning in the shin and sole to protect from bumps and bruises. Not only are these socks made in the USA, they are made in an eco-friendly manner!