1" Stacking Spacer - for all Zen Habitats enclosure sizes (set of three)Make the most of your space and stack enclosures that require no external lighting or heating. Our 1 Stacking Spacer for all Original, Meridian, and 3. 0 reptile enclosure sizes enables you to create a custom setup for your pet. The three stacking spacer bars are made of the same high quality aluminum used in our reptile enclosures, so they work perfectly together.