The Five Seasons Whole House Duct Mount HEPA Air Purifier was designed to remove airborne and household dust, coal dust, insecticide dust, mites, pollen, mold spores, fungi, bacteria, viruses, pet dander, kitchen smoke and grease, tobacco smoke, particles and larger down to 0.3 microns (1/84,000 inches) with 99.97% efficiency on the first pass of air. It is ideal for homes with limited space in furnace/air conditioning rooms. This unit is compact and can be mounted directly on the diverter valve. It can also be mounted directly on the furnace and the collar on the ductwork to save space. Ideal for homes with allergies, asthma or respiratory problems, smokers, pets, unpleasant odors and mustiness. Helps protect and prolong the efficiency of heating and cooling equipment.