Fitted diapers are more expensive then prefolds or flats but are shaped (like a disposable diaper) and most will close with either snaps or hook&loop (similar to Velcro). Unlike prefolds and flats they have encased elastic at the legs and back of the diaper (which helps contain poop). All fitted diapers need a separate waterproof or wool cover to go over it. We recommend buying one cover for every 6 fitteds in your diaper stash. This means that if you are using all fitteds, you will need a total of 24 diapers and about 4 covers (more for a newborn, less for an older baby).