Icebreaker Merino Mountaineer Heavy Cushion Mid Calf Thick Winter Socks, Zealand Merino Wool Lycra^Merino^Nylon^Spandex^Wool Made in USA Expedition weight Fully and densely cushioned mountaineering sock Reinforced toe and heel areas High loft, dense cushion throughout for maximum warmth Highly breathable insulation for temperature/moisture control Achilles instep support prevents slipping Exterior reinforcement for maximum durability