The wide expansive shelf and full-width plastic pan floor provide a generous play area and help prevent dangerous falls. Designed with customer convenience in mind we ve included critter-proof dual-locking door latches that provide a secure easy one-handed operation. Shelves include removable plastic trays for easy cleaning and are height adjustable so you can tailor the cage to your pet s needs. The Critter Nation Add-On Unit also has multiple attaching points for adding hammocks tubes toys and other accessories that are sold separately. Best of all the Critter Nation Add-On Unit is easy to assemble and attaches to your existing Critter Nation Cage - no tools required. You can accessorize your Critter Nation with the Ferret Nation Accessory Kits. Compatible with Critter Nation Models 161 & 162.