The Blueair Particle Filter 200 Series 3-stage HEPASilent filter captures 99.97% of airborne particles as small as 0.1 microns. It's made of bacteria-resistant, waterproof polypropylene and is recyclable. The filter is designed to resist clogging and won't re-release particles back into the air, even when the filter is heavily loaded. | Blueair 200/300 Series Classic Replacement Genuine Particle Filter