I am a mail carrier, so being warm is a must.  I own about 10 pair of these socks and are WONDERFUL holding the heat in and keeping your feet toasty.  The reason for the 4 stars is the fact that after 3-4 uses, the bottoms became thin and one even needed to be mended.  I've only had a few pair do this and I wear them every day in the cold months.  The company was very good at sending me a replacement pair, but the same thing happened.  Maybe a fluke, but I really hope it was just a bad batch of socks, because I've not found anything like these.  Kinda like a snuggie blanket is just a blanket, but it keeps you much warmer than a regular blanket.  That's how these socks are.