KEEN Men's Bellingham Lite 1/4 Crew Socks, Black/Black, X-Large 53% Wool/ 43% Nylon/ 3% Polyester/ 1% Spandex Made in US Y heel pockets for better fit, arch support, and Seamless Anatomical Flex Fit system reduces bunching under foot Left and right specific fit Merino wool regulates temperature and wicks moisture from skin Ravel-free double welt top keeps socks up Reinforced toe and heel for extra durability