The Darn Tough Coolmax Hiker Micro crew sockoffers cooling comfort on even the balmiest of days. The sock pulls moisture away from skin and repels bacteria and odor. The sock has an undetectable seam fusion which gives ultra smooth, invisible feel. It is made of 37% Nylon, 34% Coolmax Polyester, 26% Acrylic, 2% Lycra Spandex and 1% other fibers.