Habitrail OVO Adventure Pack, Small Animal Habitat, Hamster Accessories Habitrail OVO Adventure Pack is customizable to how you want to build it Allows your hamster plenty of space to roam around their cage The retractable roof at the top allows you easy access to your pet, and the clear plastic allows you to view your pet at all times Retractable roof also makes the hamster cage easy to clean and maintain Includes Transport Unit, 2-10 inch Trails, 1Tee, 1 Cube