Was looking for a pair of slippers to replace a worn out pair of AE from Payless that I really liked.  These are warm and comfortable and I wanted something I could run outside in.  I normally take a size 9-10 in slippers from department stores.  Since the options for this one were 8.5-9.5 and 9.5-10.5, I went up -- they're the perfect size and I could probably even wear thin socks with them.  I'm happy!