The Darn Tough Mountaineering Over-The-Calf Socks are perfect for when your out in the colder weather or when the conditions are not being kind to you. Streamlined performance fit. Chock full of Merino Wool warmth. These socks keep you moving up when the rigors of the trail get you down. Darn Tough Mountaineering Over-The-Calf Socks Features Performance Fit: No slipping, no bunching, and no blisters. Fine Gauge Knitting: Unprecedented durability and our unique “put it on, forget it’s on” feel. Fast Action Wicking: Pulls moisture away from skin. Fast drying. All Weather Performance: Cool in the summer, warm in the winter. Naturally Antimicrobial: Repels bacteria and odor. Guaranteed For Life: No strings. No conditions. For life. Merino Wool: The ultimate fiber for breathability and comfort in all conditions.