I purchased these to go with a dress for a wedding.  I can't wear heels nor flat shoes without any support.  I usually wear a size 8M in a sandal and an 8.5M in a shoe.  I ordered these in an 8M.  I wish they were a little longer and a little wider, but I think that the 9 might be too long.  No time for exchanging.  There is some arch support but not as much as I'm accustomed to.  Otherwise, very well made.  The aqua blue leather is beautiful and the straps are positioned well.  Cute sandals to dress up or down!