I wear a 10 to a 10.5 and I got size 11 - they just fit.  The footbed is the good kind soft to cushion but not be crushed flat like memory foam, however, they are totally flat (no arch support or concave area around the toes and heel), so the slides tend to move off center with no curved sides to hold your foot in place. It would have been nice if they had a least some shape to conform to your feet. The top part is adjustable with velcro so you can adjust for snuggness, but the stitching on the underside of the top part is irritating to my bare feet. Maybe if I had hair on the top of my feet it would be ok, but assuming most guys will wear these without socks, it's something to keep in mind. IMO, not worth $30 - more like $10-15.