NOTE 1. Petkit Pet Poop Bag Special Degin for Petkit Smart Cat Litter Box. 2. Size for Poop Bag : 55 x 30cm 3. 20PCS Per Roll. 4. Package Included : 2 Rolls or 4Rolls. 5. Fabric: Biodegradable Environmentally Friendly Material 6. This Product is Compatible with all Smart Cat Litter Boxes under Petkit 7. One Bag Lasts about a week for one cat. 2 rolls are available for half a year.4 rolls are available for over a year.