True HEPA filter removes 99.97% of all airborne particles as small as 0.3 microns, including pollen, dust, smoke and other sources of indoor allergens. Activated carbon pre-filter reduces odors. Patented 360 airflow and Surround Seal maximizes efficiency. Includes LifeTime HEPA filter system and Intelli-Clean electronic filter monitor to remind you when to clean the LifeTime HEPA filter and to replace the pre-filter. Air Cleaner Machine Type: HEPA; CADR: 250; Maximum Room Size (Square Footage): 374 sq. ft.; Maximum Room Size: 17 ft. x 22 ft.