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.