Filter Bros HEPA R replacement filter systems are made of two distinct parts, each designed to maximize the quality of the air you breathe. First, an activated charcoal pre filter works to remove smells and odors from the air, and captures larger particles like hair. Second, a thick HEPA filter captures smaller particles. The Filter Bros filter is designed to capture particles as small as 0.3 microns. As with all genuine Filter Bros products, this filter is both top quality and affordable. Our premium HEPA Honeywell Air Filter R is designed to maximize the quality of the air you breathe.