Size: 8.88 LBS The PetSafe Litter Box Replacement Carbon Filters help eliminate odors in your PetSafe Simply Clean Automatic Cat Litter Box. Simply slide the filter in the slots under the litter box conveyor cover. The dual-action carbon pad traps odors to keep your kitty's litter box smelling fresh. One filter can last up to four weeks. Included in the Bag 3 Carbon Filters Product Dimensions Carbon Filter: 5.5 in. x 3.2 in. x 0.2 in. Frequently Asked Questions Q: What PetSafe Simply Clean model are these filters compatible with A: These filters are compatible with model number ZAL00-16408. Q: How often should I change the filter A: The filter should be replaced every 4 weeks or as needed.