4 Degree Elite Fit SystemUses two elastics for greater stretch and recovery to keep the sock in place. IndestructawoolIndestructawool technology features a patent-pending construction method for exceptional durability and comfort. Shred ShieldSmartwool´s newest innovation, Shred Shield technology reinforces the toe cap with minimal cushiioning, to combat excess friction from the top and front of toenails. It increases durability by 3x and is found in all of our zero cushion, 200-needle Performance and Everyday socks. Virtually SeamlessSmartwoll have smoothed out there toe seams for ultimate in-shoe fit and comfort. This technology is found in Smartwool´s Performance and Everyday socks.