Tested strong, the KEEN Olympus Lite Crew is the most durable sock on the trail. Dura-Zone high-tenacity nylon fibers – weight for weight stronger than steel – are blended into the heel and toe area for comfort, durability, and strong abrasion resistance. Right-angle Heel Hold cup construction provides a secure, natural fit. A Wunderseam seamless toe in the flex zone helps eliminate bunching, while the left and right foot design further optimizes the fit. 47% Merino wool, 36% nylon, 11% Dyneema polyethylene, 3% polyester, 3% Lycra spandex fabric. Built in the USA.