Advanced, optimized warmth without added bulk, Simms’ Midweight OTC Sock is powered by a 75-percent merino wool blend that delivers moisture management and anti-microbial protection. Midweight over the calf engineering bolsters coverage while keeping your temperature range permanently tuned. Extended high-loft toes add warmth where it counts. And Right Angle® arch support improves overall support across rugged trail and river conditions. Made in the USA.