MidWest Homes for Pets Critter Nation® Add-On Unit adds more space to your existing Critter Nation Cage for small animals. Small animal clubs and individual owners around the world use Critter Nation habitats to house their pet rats, chinchillas, sugar gliders, hedgehogs, degus, and more. The Critter Nation habitat features doors that open fully, critter-proof door latches, large adjustable leak-proof shelves with anchor points for toys or bedding, wire ramps with Happy Feet Ramp Covers, and sturdy, leak-proof, removable plastic pans for easy cleaning. Give your small animal a happy home with Critter Nation, the World’s Best Small Animal Habitat.