The Wigwam F2230 40 Below Sock, is an extra cushioned thermal boot sock. The F2230 features an extra-smooth reverse toe closure and is fully cushioned throughout the entire sock. Excellent for cold climate use, the 40 Below is made of 50% Wool, 48% Nylon, and 2% Spandex. Great for work and play.
For a sock called "40 below", I would have expected a little heavier sock. These are relatively light weight - about the same as any off-the-shelf wool sock. It does have a nice deep pile to it, and is somewhat warm when dry, but it gets cold pretty quick once it absorbs some sweat.