Size Chart Smartwool's best fitting, most advanced run socks yet. There's years of testing, prototypes and running smarts packed into these socks. Featuring Light Elite cushioning in the ball and heel of the foot for ultimate shock absorption with minimal in-shoe volume, men's-specific mesh ventilation zones and a Virtually Seamless(TM) toe. Features: - PhD(R): Built for Performance in the Highest Degree - 4 Degree Elite Fit System: Uses two elastics for greater stretch and recovery to keep the sock in place - Indestructawool(TM) technology features a patent-pending construction method for exceptional durability and comfort - Mesh ventilation zones provide optimum moisture management and maximum breathability - Light Elite Cushioning: Maximum impact protection with targeted cushioning on the ball and heel of the foot. Designed specifically for runners - Sock Height: Micro - Virtually Seamless(TM) toe - Achilles tab - Made in USA of Imported Yarns: 57% Merino Wool, 40% Nylon, 3% Elastane - Only available to ship within the USA - Last Chance: Discontinued Style