I have wide feet so I first ordered these in the 8.5W. The description said that the strap was adjustable but when they arrived, the strap wasn't adjustable so they were too tight and I couldn't comfortably get my feet into them. So, I re-ordered them in the 8.5WW and they fit much better. However, I really wish the strap was adjustable. So if you have wide feet or a high instep, you might have to try the extra wide.