From the New York Baby Show website: "...High-quality crib sheets are a must to keep baby safe and comfortable during the early years–and B.Sensible’s crib sheets pass the test with flying colors. “Since the sheets are waterproof there is no need for an additional waterproof mattress cover. When the baby leaks through his/her diaper the urine will be contained to the sheet and would not have leaked down to the mattress cover,” one judge notes. “This means less laundry to have to do and less of a mess and work to deal with during the middle of the night sheet changes. Also, the sheets are incredibly soft and eco-friendly.” us.bsensible.com