The PhD® Ski Light helps keep your feet warm and dry even on the longest days. We placed cushioning where skiers need it most: on the shin to banish shin bang and on the bottom of the foot for warmth and impact protection. Patent-pending Indestructawool™ technology provides ultimate durability to make sure your socks are ready to go, run after run. Made with our 4Degree® elite fit system for a sock that doesn't bunch, slip, or bind.