POWERFUL AIR PURIFIER - BlueDri's Air Shield 550 HEPA Air Scrubber delivers at least 40% more CFM than leading competitors in the category. It removes harmful airborne particles including smoke, pet dander, pollen, saw dust, and other miscellaneous debris. HEAVY DUTY - AS-550 operates at 3 different stages, each offering its own unique contribution to purifying air. The pre-filter protects the prime HEPA filter acting as a large particle cleaner allowing the HEPA filter to do the finer work. Ideal for commercial repair and construction sites and sewage remediation, water and fire damage restoration. PURITY - HEPA filter removes 99