The Smartwool Hike Classic Edition Full Cushion Second Sock adds extra warmth, durability, and protection for the coldest days on the trail. It's built from 2nd Cut(TM) yarn, a blend of recycled fibers from Smartwool's own sock take-back program and manufacturing waste combined with virgin Merino wool, so the warmth doesn't come at the cost of doing more with less. A Virtually Seamless(TM) toe keeps the fit smooth, and the sock dries quickly and wicks moisture to stay comfortable even as conditions change underfoot. What Our Gearhead(R) Experts Are Saying:"I wore these on a below-freezing hike and my feet were the last thing I worried about all day."