Smartwool Mens Phd Running Light Elite Low Cut Socks. 4 Degree™ elite fit system uses two elastics for greater stretch and recovery. Run-specific fit. Patented ReliaWool™ technology in high impact areas increases durability Mesh ventilation zones designed around a man’s foot. Virtually seamless toe 200 needle construction provides high-density cushioning while maintaining light weight 2.25" overall height Knit In USA Of Imported Yarn: 56% Merino Wool, 40% Nylon, 4% Elastane