Smartwool put all of its smarts into these new and improved Women's PhD(R) Run Ultra Light Micro socks. You won't break your stride, thanks to Indestructawool technology designed for added durability and an Achilles tab designed to help prevent sock slippage. And by adding brand-new Shred Shield technology, the wear and tear from toes is reduced, helping you push toward your finish line and achieve higher mileage. 48% merino wool48% nylon4% elastane. PhD(R): 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. Indestructawool technology features a patent-pending construction method for exceptional durability and comfort. Multi-sport design. Ultra Light cushioning. Body-mapped mesh ventilation zones. Virtually Seamless toe. Shred Shield technology, Smartwool's newest technology, reinforces the toe cap with minimal cushioning. The result reduces excess friction from the toe and around the toenails and increases durability three times. Achilles Tab prevents sock from slipping down into shoe. Imported.