Fellowes True HEPA Replacement Filter for AP Series Air purifiers captures 99.97% of particles and impurities as small as 0.3 microns, including mold spores, pollen, dust mites, most airborne microbes, allergens and cigarette smoke. For use with Fellowes air purifiers, which are sold separately. Perfect for use in the office, home office, school, or anywhere you would like to filter the air around you.