About this item The RFL focuses on the important stuff: durability, breathable warmth, and ultra-lightweight fit. It's the spot-on choice for serious skiers and riders. This go-to women's Snow sock features a reinforced heel that strengthens the sock without needing a dip in the river Styx. Lightest sock Darn Tough makes. Ultra-Lightweight, Over-the-Calf Height. Merino Wool: The ultimate fiber for breathability and comfort in all conditions. Still made in Vermont, USA. Still unconditionally guaranteed for life.