The QuietClean air purifier offers high efficiency air cleaning with permanent washable filters saving you money with expensive replacement filter costs**. The permanent filter helps remove up to 99% of airborne particles such as smoke dust pollen pet dander and mold spores. Compared to ionic air purifiers the filter from the HFD-120-Q captures 17 times more pollutants . This superior cleaning performance is due primarily to the fact that our model uses a fan to effectively circulate the air throughout the room forcing particles through a 3-step filtration system. With whisper quiet operation the QuietClean air purifier circulates and filters the room air every 12 minutes. The permanent filter is easy to clean - simply rinse in water 4 times a year. An electronic filter indicator illuminates to remind you when to clean the filter. This model is recommended for medium to large size rooms. It's attractive sleek tower design and quiet operation makes it ideal for any room in your home.