I usually wear an 8.5 wide and got a 8, which fits fine. My foot fits completely in the soft 4D foam base. The strap holds my feet in securely. The velcro to hold your foot in is an circle of Velcro about an 1.5 inches. Because my foot is wider the edge of the Velcro on the bottom is slightly exposed, the Velcro circles don't match up perfectly.

Great sandal for the gym and chores around the house.  They are comfortable, fit well, and stay on.