This is my second pair of these.  I bought these for flying.  My ankles freeze on airplanes.  I wanted something that would be warm, but could be easily slid into sandals to get the the on flight bathroom.  These are perfect for that.  They are compact and very light in the stuff sack that came with them.  Plus, I have used them for extra warmth when camping and for keeping my feet and ankles warm after knee replacement surgery when my polar ice machine made me freeze.  These are indispensable for me!