A sock for serious adventurers, the Explorer Merino Endurance Boot sits at an ideal height for boots with an extended ankle cuff. Featuring cushioning throughout for warmth and engineered advanced zonal padding system for support and comfort, this is the ultimate sock for long or multiday high mountain and winter expeditions. Merino Performance Fusion Technology provides resilient padding, balanced insulation, moisture wicking and outstanding durability for all day comfort. The Performance Fit is close and supportive and won't slip down, or bunch in your footwear no matter how long the day. The toe box is closed with an insulated Flat Toe Seam to prevent cold spots and the sock is kept securely in place with an Elasticated Arch and 3D-shaped heel cup. Built on a structure of Lycra® and set by our Thermo Fit process ensures the sock returns to its original shape and size after every wash. Tested by Explorers in the coldest, most extreme places on this planet this sock delivers more comfort and warmth than any other Bridgedale sock and is the ideal choice for cold-weather expeditions.