KEEN Men Boulder Canyon Crew Mid Sock,Grey/Steel Blue,Medium 61% Wool/ 35% Nylon/ 3% Polyester/ 1% Spandex Made in US Y heel pockets for better fit, arch support, Seamless Anatomical Flex Fit System reduces bunching of material underneath foot and reinforced toe and heel for extra durability Hiking sock with cushioning from the top of the welt to the bottom of the toe for impact reduction and moisture management Left and right specific fit Merino wool regulates temperature and wicks moisture from skin Ravel-free double welt top keeps socks up