First and foremost, I wear a size 16 shoe, and the Large fit me perfectly. It's always a gamble when I get socks, but these were perfect.Second, I can't speak to extreme low temperatures some outdoorsy types might encounter, but I am someone who is too damned cheap to turn my heat up too high in the winter, and these keep my feet nice and toasty.They don't roll down, but also don't "strangle" my calves. If you're newly working from home, I highly recommend the ones with "grips" on the bottom to