We were a little confuse by the sizing choices listed, but I'm not sure if that is Amazon's fault or ours.  The bottom has a nod skid pattern on it which we are sure will be great for our wood floors.  The item was very comfy.  Unfortunately, we had to return it because I was sure the size would not fit my son's foot, which is a 10.5, for a decent amount of time.  He is still growing.  His dad, who has size 12 feet tried them on and, of course, found them to be very snug.

We returned these for a larger size.

New update:  Son loves the feel and warmth of these slippers.  Only problem I can see is that the non skid pattern is already wearing off in the shape of his foot pattern and he has only worn these a week.