The Vornado AC550 whole-room air purifier uses two filters to provide three-stage filtration. The carbon filter captures odor particles and acts as a pre-filter, capturing larger particles. The true HEPA filtration removes up to 99.97% of airborne allergens down to 0.3 microns. It cleans air up to 335 feet and features 4 speeds; electronic, push-button controls; filter replacement indicator; sleep mode and a five-year warranty. It includes 2 HEPA filters and two carbon pre filters.