Aftermarket 200 series & 300 Series Particle Replacement Filter Designed and engineered by Breathe Naturally Captures 99.97% of harmful particles such as dust, pollen, and smoke down to 0.1 microns in size Naturally anti-bacterial to prevent bacteria and mold growth, made of 100% recyclable materials Gradient filter structure resists clogging for maximum airflow, never re-releasing harmful particles Designed to fit 201, 203, 215B, 250E, 270E, and 303 air purifiers