Pure Air 2-in-1 Active Carbon and Allergy+ Replacement Filter for PU3030 and PU3040 Air Purifiers. Filters for Smoke, Unpleasant odors, Chemical pollutants, Volatile Organic Compounds (VOC), Allergen and Pollen, Dust mites, Germs and Molds, Bacteria and Viruses. It is recommended to replace this filter every 12 months ( may vary depending on location and use)