Brolly Sheets products are made from low allergy cotton, not polyester. This ensures that they’re soft and comfortable enough to allow your child a good night’s sleep, and helps to reduce their exposure to allergens.The Brolly Bed Wetting Sheet Pads are designed with a soft, 100% cotton top and a breathable waterproof back. They’re also designed to be quiet, so even if your child is a restless sleeper, they won’t be kept awake by annoying rustling sounds made by the sheet pads.The Brolly Waterproof Fitted Sheet and Brolly have been manufactured with the same idea in mind — a soft, cotton top layer with a waterproof layer beneath.