Honeywell True HEPA Tower Air Purifier. The Doctors Choice - #1 brand recommended by allergists. True HEPA filter captures up to 99.97% of airborne allergens, 0.3 microns and larger; activated carbon pre-filter helps reduce unpleasant odors; 3 cleaning levels. Energy Star rated. Circulates room air up to 5 times an hour; emits no ozone from filtration process; estimated room size: 170 sq. ft (13x13). Replace HEPA filter 1 x per year. 5 year warranty.