SmartWool PhD Cycle Ultra Light Pattern Crew Socks - Past Season 49% Merino Wool, 47% Nylon, 4% Elastane Virtually seamless toe Ultra Light Cushion: Non-cushioned for maximum performance in close-fitting cycling shoes. 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. Style: SW0SW224 Sock Height: Crew: 8&quot; overall height Strategically placed mesh ventilation zones provide ventilation for temperature and moisture management. Knit in USA