Smartwool Women's Phd Run Ultra Light Mini Performance Socks, Silver, Large 100% Wool Knit in USA of 52% Merino Wool, 44% Nylon, 4% Elastane New 4 Degree Elite Fit System uses two elastics for greater stretch and recovery to keep the sock in place Patent pending ReliaWool Technology in high impact areas provides the longer lasting protection to keep feet comfortable Low profile and durable virtually seamless toe Alternating 1x1 welt Single layer 1x1 ribbed top