SmartWool Men's PhD Run Graduated Compression Ultra Light Socks - Past Season 50% Merino Wool, 41% Nylon, 9% Elastane Knit in USA Graduated Compression Ultra Light Cushion: Minimal cushioning for maximum next-to-foot performance without added bulk. Venting: Men'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. 20-30 mmHg graduated compression rating - Graduated compression to reduce fatigue and speed recovery -Virtually seamless toe 207 needle construction provides highest knit density while maintaining ultra light weight Sock Height: Over the Calf: 14" overall height Style: SW0SW127