these waterproof covers fit snug around your baby's diaper. they all come with a small pocket in the front of the cover, so that one may tuck a prefold into it and fan it out in the back. because the cover is snug fitting, you may not even have to use pins. these covers are especially made for esbaby diapers, however, will likely fit over any fitted cloth diaper. if ordering as a swim diaper, you may want to order a size down. now available with colored fold over elastic.