The water-repellent roll-top backpack in the Happy Camper Edition . The Doughnut Christopher backpack is made from 600D polyester and is part of the Happy Camper series. The Rucskack is water-repellent and offers safe and easy access with a practical roll-top closure. It has a laptop compartment for up to 15-inch devices and the padded, adjustable shoulder straps ensure a high level of comfort.