Darn Tough Men's RFL Over-the-Calf Ultra Light Sock The RFL's silky Merino Wool is the lightest we offer. Skiers and riders seeking a streamlined boot connection can rejoice in the combo of breathability, feel and guaranteed durability. 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. True Seamless(TM): Undetectable seam fusion for an ultra smooth, invisible feel. 55% Merino Wool 42% Nylon 3% Lycra(R) Spandex