I don't usually wear ballet flats, but I needed one for work.  I thought my best bet was a pair of Aerosoles: guaranteed comfort.  However, when I received these, after wearing them for about two hours, they were rubbing at the back of my heals and made them very sore.  I tried wearing them with stockings, which did help, but by the end of the day, my feet were hurting.  Not what I expected at all.  These are very narrow to the front, but wide towards the back.  The fit is not good.