Compatible with GermGuardian Air Purifiers (models AC4825, AC4825E, AC4825DLX, AC4300BPTCA, AC4850PT, AC4900CA, CDAP4500BCA, CDAP4500WCA), PureGuardian Air Purifier (model AP2200CA), and Black & Decker Air Purifier (model BXAP148) The Filter Bros Filter is a high efficiency absorber. As with all genuine Filter Bros products, this filter is both ultra-high quality and affordable. This genuine Filter Bros filter is made of two distinct parts, both designed to maximize the quality of the air you breathe. First, an activated charcoal layer removes odors from the air and captures larger air particulates. Second, a thick filter captures small particles. The Filter Bros filter is designed to capture particles as small as 0.3 microns. The Filter Bros recommend replacing filters every 6 to 9 months with average use.