Simms’ Thermal OTC Socks stoke a fire under your feet thanks to premium merino wool—for trusted moisture management and appreciated anti-microbial performance. Socks are finished with nylon, polyester, and LYCRA® stretch for a full suite of comfort-enhancing benefits. The high-loft, over the calf design maximizes warmth while Right Angle® arch support improves overall support across variable trail and river conditions. Made in the USA.