The Habitrail Ovo Den is an additional area for your hamster to explore and enjoy. With its clear plastic retractable roof the Habitrail Ovo Den gives easy access to your pet. The Habitrail Ovo Den can be used as a toilet or as a sleeeping area. (If your hamster is using the Habitrail Ovo Den as a toilet please remember that this will need cleaning more often.) The Habitrail Ovo Den can be cleaned with warm water and mild detergent and rinsed throughly. You can add more than one Habitrail Ovo Den to your Habitrail Ovo which will give your hamster both sleeping and toilet areas. Fully combinable with all Habitrail Ovo pieces to create a play and living area as big as your imagination for your hamster.