When I saw these in the package I was skeptical, however, I decided to give them a try.  They are fabulous.  I used them in my boots.  For the first time that I can remember my feet stayed warm.  They don't have the bulk of "winter" socks so they don't make your boots pinch.  There are non-skid bumps on the bottom so you won't slide around before you put your boots on.  They didn't bother me at all.