I originally bought these to replace another pair of Old Friend slippers that finally wore out after a few years.  These slippers have the removable insole but they lack the memory foam comfort of some of the other same brand slippers.  I wear a 10.5 mens and so I ordered the 11 mens.  They feel snug, but not discomfortably snug, and being they're leather, they will stretch.  I have to say, I am disappointed in these slippers as they don't keep my feet warm without wearing socks with them.  The bottom soles are fantastic as it is very flexible and there are no high or low spots.  I am still happy as these slippers are comfortable but they don't provide the insulation nor padding that I have expected from Old Friend.