Smartwool Women's PhD Run Light Elite Micro Indestructawool technology features a wool-based, patent-pending yarn and construction method for exceptional durability and comfort. 4 Degree elite fit system uses two elastics for greater stretch and recovery. Narrower profile provides perfect women's-specific run fit Mesh ventilation zones designed specifically for female runners provide optimum temperature regulation and moisture management Virtually Seamless toe Achilles tab; 200 needle construction provides high-density cushioning while maintaining light weight; 1.5" overall height