The Darn Tough Hiker Coolmax Micro Crew Light Grey features Coolmax?Â« that moves moisture away from your skin and dries fast. The women's sock features fine gauge knitting, fast action wicking and true SeamlessT to offer an ultra smooth, invisible feel. The sock is guaranteed for life and is naturally antimicrobial. The micro crew height sock is built light, darn comfortable and super strong to provide a lightweight, sure fit. It comprises of 39% nylon, 34% coolmax?Â« polyester, 19% acrylic, 5% polyester and 3% lycra?Â« spandex.