Dri-Eaz F284 DefendAir HEPA 500 Air Purifier Negative Air Machine Air Scrubber Portable air scrubber and negative pressure machine with two-stage filter system and variable air flow control of 250 to 500 CFM for mold and sewage remediation, water and fire damage restoration, and dust and odor control First stage standard paper pre-filter captures large particles, second-stage primary HEPA filter rated to capture 99.97% of remaining particles down to 0.3 microns 8" air outlet fits Dri-Eaz rigid engineered ducting (sold separately) for negative pressure applications. Daisy chain capability - link up to 4 units on 1 power outlet Draws 3 amps on a 115V power supply, and has an auxiliary power outlet that allows users to connect up to three units together for combined air flow speeds of up to 1500 CFM Rotomolded polyethylene housing provides consistent wall thicknesses and strong outside corners for resistance to damage.Static pressure: 2.9 inches (H2O)