Arm & Hammer Universal Cat Odor Filter helps reduce & absorb unwanted odors in your litter box area for up to 3 months! Arm & Hammer Litter Box Filters are double the odor & moisture protection combining Natural Charcoal & Zeolite. Replacement filters use Zeolite/Charcoal particles to trap airborne odor molecules. Absorbs odors & keeps air clean while being nontoxic & easy-to-load. Filter designed to fit both Large & Jumbo Litter Pans.