Breathe easy. Bringing together smooth Merino Wool feel, next-to-skin fit, flex and fatigue-zapping arch support, and targeted venting — the ultra-lightweight RFL is the sock experience your hard-charging feet have been dying for, lap after lap. Performance Fit: no slipping, no bunching, and no blisters Fine Gauge Knitting: unprecedented durability andunique “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 Merino Wool: the ultimate fiber blend for breathability and comfort in all conditions Ultra-Light: lightest sock for race day or anyone looking for a lighter-than-air feel from a tougher than hell sock Over the Calf Height: the ultimate height for keeping the outside—out Made in Vermont, USA Sustainability: from responsible sourcing practices to livable wages in our communities, Darn Tough Vermont® is committed to progressive, positive, growth Recommended care: to help ensure many happy miles with your Darn Tough Vermont® socks, wash them in warm water on gentle cycle with socks inside-out; do not bleach; tumble dry on low; do not dry clean Size Chart Medium fits Men's shoe sizes 8-9.5 Large fits Men's shoe sizes 10-12 XL fits Men's shoe sizes 12.5-14.5 Product Features: Fabric:55% Nylon, 42% Merino Wool, 3% Lycra® Spandex Darn Tough Vermont Men's RFL Over-The-Calf Ultra Light Cushioned Ski & Snowboard Sock