Petmate Dosckocil CDS29203 Basic Cat Litter Box Zeolite Filter, Jumbo Litter Box Filter helps reduce & absorb unwanted odors in your litter box area for up to 3 months Absorbs odors & keeps air clean while being nontoxic & easy-to-load Petmate Zeolite-Charcoal Replacement Litter Box Filter uses Zeolite/Charcoal particles to trap airborne odor molecules