The Smartwool(R) Trekking Heavy Crew Socks keep your feet comfortable and warm throughout the day. Fully cushioned for shock absorption, these trekking crew socks feature an arch brace that holds the socks in place for additional support. Flat-knit toe seams provide all day comfort while participating in outdoor activities. The Trekking crew socks are made with WOW Technology(TM) in the sole for durability and extreme comfort. FEATURES: Trekking socks WOW Technology(TM) in reinforced sole for maximum comfort and durability Heavy Full-cushioning protects against the elements Arch brace holds sock in place Flat-knit toe seam Fabric: 80% Merino wool / 19% Nylon / 1% Elastic Style: 131 SIZING: Sock Size: Small = Shoe Size: Men's 3-5.5, Women's 4-6.5 Sock Size: Medium = Shoe Size: Men's 6-8.5, Women's 7-9.5 Sock Size: Large = Shoe Size: Men's 9-11.5, Women's 10-12.5 Sock Size: X Large = Shoe Size: Men's 12-14.5 Click here for additional information relating to the Manufacturer's Warranty.