Includes 2 sets of filters for use with the Bionaire Odor Grabber Litter Box 78800-100. Advanced odor filter targets and traps litter box odors through a proprietary blend of activated Carbon and Zeolite. The odor filter works through a process called adsorption, where specific odor molecules are trapped and held by the filter. A specialized pre-filter removes harmful dust, dander and fur as they pass through the filter. Filters last up to 8 weeks although actual life varies based on number of cats, scooping/cleaning frequency, location, etc.