Waterproof breathable covers were invented by a mother to help reduce the amount of nappy rash her son suffered from when they moved from the USA to Hong Kong. Her initial crude efforts were gradually refined to become the Diaperaps we know today, and we now have a range of breathable, but waterproof covers to choose from. They generally consist of polyurethane bonded to a nylon, polyester or cotton outer. They are soft, stretchy, durable and easy to care for, almost all are machine washable. Some have easy velcro fixings, some have poppers and there are also pull on styles.