SmartWool Men's PhD Run Light Elite Micro Socks ( 51% Merino Wool, 46% Nylon, 3% Elastane Made in USA Ultra Light Cushion: Minimal cushioning for maximum next-to-foot performance without added bulk. 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. Men's-specific mesh ventilation zones provide additional breathability and moisture management. 200 needle construction provides high-density cushioning while maintaining light weight. Virtually seamless toe - Achilles tab Sock Height: Micro - 1.75" overall height Style: SW0SW167