My feet tend to get cold fast, and I don't like wearing my shoes in the house because I like being able to slip them on and off.  I purchased these through Amazon, and when they arrived, I put them on to try them out.  I too have also been concerned about shoes without backs slipping off, and am very surprised that these don't slip off.  I put them on, and no matter how cold my feet are in about 5 minutes they warm up.  (When I started typing this, my feet were cold to the bone, but now they are pretty warm.)  They are very soft inside, and seem to be a pretty durable slipper.  The traction on the soles is nice too.