Jambini Zipper Waterproof Crib Mattress Cover. Amazon users say: "My favorite thing about this specific mattress cover is that it zips around the mattress so that both top and bottom are covered, this prevents the mattress cover from curling up over the corners or sliding off of the mattress." and "the cover was easy to put on, in fact, easier than the stretch ones that just go over the top". Built to last, this high quality mattress protector has the ability to withstand hundreds of washer/dryer cycles without any shrinkage so you can relax knowing you are getting great value. Provides all the benefits of a waterproof liner without the annoying crinkly sound.