What we used to call "puddle pads," waterproof pads, 'bout two feet square. They are kindasorta rubberised on one side, and fuzzy on the other. Put 'em under the little guys when they sleep, when you are changing diapers, etc. Mucho more better than having to swap out crip sheets at Oh Dark Thirty. They are getting to be hard to find, but we found some for our newest grandson at K-mart (or was it Wally? Don't remember, but I think it was K). Get a bunch of them...