The ultimate combination: Merino wool for cold weather insulation and the performance that comes from a perfect fit. There is no other heavyweight sock that can make this claim. If there were, we would have made it! This sock is loaded with 100% Merino wool on the inside against your foot, so all you feel is comfortable and dry. Heavyweight full-foot cushioning for warmth and protection. Durable nylon exterior for extended wear. Over-the-calf length falls just below the knee.