I have 4 pairs of Smart Wool socks... They are the best that I've ever worn. I was up in Canada a few weeks ago and it was really wet and cold out. I was wearing a pair of polypropylene sock liners w/ the Smart Wool .. my feet started to get chilled just a tad... took my boots and socks off.. and the liners were a little damp.. took them off.. and put on just the straight smart wool socks.. and my feet warmed back up. I was quite amazed.