Fox River Backpacker Mid-Calf Socks 90% worsted wool, 9% stretch nylon, 1% spandex. Fox River's patented Wick DryHealth Systemis designed to help keep feet dry and comfortable, no matter what the temperature High-performance socks protect feet against cold or excessive heat and assist the foot's own temperature regulating function Fox River uses a combination of natural and synthetic fibers to help keep feet dry and comfortable