Odor/Gas Reducing Universal Pre-Filter The Honeywell Odor-Reducing Pre-Filter enhances the efficiency of your air purifier by adding an extra layer of filtering material. This pre-filtering blanket prolongs the life of your HEPA filter. Deodorizes the air, reducing odors with activated carbon and zeolite. Fits 17000, 17005, 17007-HD, 50250, 50255-HD, 18150. This pre-filter helps capture certain household gases such as ammonia and the gases from cleaning products, paint and furnishings Captures larger particles such as dust, lint, fibers & pet fur, maximizing the HEPA filter life Replace every 3 months to maintain freshness Package contains 1 large pre-filter. The perforated design makes 1-8 pre-filters depending on the air purifier model Fits all Honeywell Round, QuietCare, & SilentComfort Air Purifiers including: 10000 series, 17000 series, 18100 series, 40000 series, 50000 series, 60000 series Honeywell Console Series This product does not reduce or absorb carbon monoxide gas.