SmartWool Women's PhD Ski Light Socks - Past Season 61% Merino Wool, 38% Nylon, 1% Elastane Light Cushion: Light cushioned sole, shin and calf for impact absorption. Mesh Venting: Women's-specific mesh ventilation zones provide additional breathability and moisture management.PhD = 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. ReliaWool: Patented ReliaWool technology in high impact areas provides superior durability. Narrower profile provides perfect women's specific fit - Flat knit durable toe seam Sock Height: Over the Calf - 13" overall height Knit in USA of Imported Yarn New 4 Degree Elite Fit System uses two elastics for greater stretch and recovery to keep the sock in place