The Vornado AC350 Whole Room Air Purifier uses HEPA filtration to remove up to 99.97% of airborne allergens down to 0.3 micron in size. The AC350 uses a radial blower to intake and clean the air in rooms up to 135 square feet precision engineering allows the blower to operate quietly, despite its powerful air flow. It features 3 speeds, push button electronic controls, and filter replacement indicator.