Hi-Tec Mid-Weight Hiker Crew Sock acrylic 65% Hi-Bulk Acrylic, 22% Merino Wool, 11% Nylon, 2% Spandex Merino Wool aids in moisture management, Full Thermal Construction helps reglate tempratures within the socks, Arch Compression secure sock around the foot to reduce sagging, Ribbed Leg conforms around the calf helping to keep socks in place, Welt Top works injunction with rib leg to hold socks up Machine Wash - Warm, Tumble Dry- Low, Non Chlorine Bleach as needed USA