I love them!  They are very warm and have slightly more support that the usual slipper.  The rubber sole on the bottom allows me to run outside to get the mail or throw the ball for the dog.  I'm typically between an 8.5 and a 9 in shoes and got the 9 in these.  They fit fine, however an 8.5 would probably be better - I'm guessing an 8 would be too small.  The sheepskin compacts a little after time and there is some more room in them than when originally purchased.