These just might be the best fitting and most advance socks you will ever put on your feet. With years of testing, prototypes, and running smarts packed into these merino wool socks, your comfort will be maximized with minimal in-shoe volume. Featuring cushioning in the ball and heel of the foot and body-mapped mesh ventilation zones. Made In USA. 56% Merino Wool, 41% Nylon, 3% Elastane.