Honeywell 18155N SilentComfort Permanent, True HEPA Air Purifier Air purifier with HEPA filter for rooms up to 225 square feet Removes up to 100 percent of bacteria and germs that pass through HEPA filter never needs replacement Easy to clean with household vacuum twice a year Electronic filter clean reminder; quietly cleans the air with no cold exhaust draft Designed for ultra-quiet, high-speed air purifying, Honeywell's SilentComfort HEPA air purifier removes at least 99.97 percent of airborne particles as small as 0.3 microns from rooms up to 225 square feet. The unit's no-draft technology provides efficient air cleaning without the cool-air exhaust. An Intelli-Check indicator lets you know when the filter needs to be cleaned. The SilentComfort also features two filtration systems; a true HEPA filter, and a carbon pre-filter that keeps larger particles from clogging the HEPA filter and helps reduce household odors. The purifier is equipped with a 3-speed fan that speedily removes dust, pollen, tobacco smoke, and cat dander from the air. The purifier also helps reduce airborne germs, bacteria, mold spores and fungus with up to 100-percent efficiency as well. And, the unit's advanced airflow design provides ultra quiet operation while room air is fully processed once every 12 minutes. The permanent HEPA filter is easy to clean and only needs it twice a year under normal circumstances. No more expensive HEPA filters to replace!