Zeolite Litter Filter, For Use With Booda Clean Step Dome Litter Pan TV #136-636, Helps Reduce & Absorb Unwanted Odors In Your Litter Box Area For Up To 3 Months, Uses Zeolite/Charcoal Particles To Trap Airborne Odor Molecules, Absorbs Odors & Keeps Air Clean While Being Non-Toxic, Easy To Load.