The Mountaineer socks are the thickest, warmest performance socks to offer. Designed for rugged environments where the best gear matters. Anatomical extended welt provides additional coverage and comfort. 4 Degree™ Elite Fit System designed for a dialed-in, performance-oriented fit. Virtually Seamless™ toe for enhanced comfort. Merino wool helps manage moisture, regulate temperature, and resist odors. Indestructawool™ technology with extended durability zones.