if you have not own a pair before be aware you will probably have a break in period , but after a few wear these begin to form to you foot and instantly become fave . I have own the single layer and I have to say that the double layer really do make a difference in the arch support . if the strap break Rainbow will take 'em back as long as you have not wear into the next layer . I wear the guy sandal because I have wider foot and they fit just right !