Size Chart Smartwool put all of their smarts into these new and improved run socks that feature a 4 Degree(R) elite fit system, Indestructawool(TM) technology for superior durability and a Virtually Seamless(TM) toe. Women's-specific mesh ventilation zones provide ultimate temperature and moisture regulation where female runners need it most. Features: - Women's specific fit; narrower heel and slimmer fit - 4 Degree(TM) Elite Fit System for a dialed, performance-oriented fit with flex zone at ankle joint - Indestructawool(TM) technology features a patent-pending construction method for exceptional durability and comfort - Mesh ventilation zones provide optimum moisture management and maximum breathability - Minimal cushioning for maximum performance in close-fitting shoes - Sock Height: Micro - Virtually Seamless(TM) toe - Achilles tab - Made in USA of Imported Yarns: 49% Merino Wool, 47% Nylon, 4% Elastane