Letting your hamster roam to different areas the Habitrail Ovo Adventure Pack allows your hamster to choose between going for a sleep in the den burrow his way to the transport unit and then go back down for a nibble in his pad. The Habitrail Ovo Adventure Pack contains a transport unit 2-10" trails 1 tee 1 cube den 5 windows 3 elbows and 10 lock connectors along with clear plastic retractable roofs on the transport unit and den to allow easy pet access. Fully combinable with all Habitrail Ovo pieces to create a play and living area as big as your imagination for your hamster.