The QUAD-PRO is a potent bi-polar ionizer utilizing needlepoint ionization to improve your homeís air quality. This system releases positive and negative ions into your air stream through its unique Venturi Emission system. The four needle discharge posts optimize ion output to help cluster airborne allergen particles, microbes, and other pollutants. When installed in your central heating and cooling system, the QUAD-PRO treats indoor air around the clock. The bi-polar ionization process works through agglomeration ñ positive and negative ions constantly emit from the Venturi needle posts and attach to allergens like pollen, dust, animal dander, microbes, and other pollutants. This clustering effect makes contaminants larger and heavier, causing them to fall out of air streams or get trapped by your filtration system. The system is UL 2998 certified and CARB certified, meeting Californiaís strict ozone emission limits. The active ions also help control contaminant buildup on your evaporative coils and help prevent biofilm growth.