The Smartwool Liner Crew can be worn as an ultra light sock on warm hikes or as a liner in cold weather. The ribbed cuff keeps it from sliding into your hiking boots or bunching at the bottom of your outer-layer sock. A flat-knit toe seam won't bother your toes while breaking trail. Smartwool designed the Liner Crew Socks to prevent blistering as well as odor; feel free to layer without fear of grossing out your mountaineering buddies. We recommend bringing two sets of Liner socks, one to wear on your way up to Camp Muir and then a fresh set for your summit day.