Using HEPASilent® technology the 200/300 Series Particle Filter removes particles such as pollen, dust, and pet dander from your indoor environment with 99.97% accuracy, down to 0.1 microns in size. The 200/300 Series Particle Filter is designed specifically as a replacement filter for the Blueair 201, 203, 215B, 250E, 270E, and 303 air purifiers. The gradient structure of the ultrasonically bonded filter fibers allows the use less dense filter media, so you get greater airflow with lower air pressure, resulting in a whisper silent clean air delivery. The naturally anti-bacterial fibers prevent bacteria and mold growth, and are made with 100% recyclable and chemical free materials, so the only thing you’ll add back into your environment is clean air. The filter in your air purifier should be changed every six months.