The SilentComfort True HEPA air purifier removes at least 99.97% of common household particles as small as 0.3 microns from the air passing through it such as dust, pollen, mold spores, tobacco smoke and cat dander. The carbon pre-filter helps remove common household odors while helping to extend the life of the HEPA filter. This air purifier also features SilentComfort advanced airflow design for ultra quiet high speed operation. The No Draft Technology feature provides air cleaning without a cool exhaust draft and the Intelli-Check filter monitor reminds you when to replace the filters. Recommended for medium to large rooms.