4'x2'x4' Extension Kit 3.0Do you want to give your pet even more room to run, jump and climb? The Extension Kit, for 4x2x4 3. 0 Zen Habitats reptile enclosures, lets you expand your vivarium and make it a custom, larger space your pet will love. With the kit, you can combine enclosures to expand your setup either lengthwise or depthwise (cannot be used to add height) to make your setup 6', 8, 12', or even larger. Popular enclosure combinations: Two 4x2x4 enclosures = One 8x2x4