QuietFlo 99.97% Effective to 0.3 Microns. Changes the Air up to 6 Times Per Hour. 30% Better Odor Reduction. Digital LCD Controls. LCD Filter Change Indicator. 3-Speed Whisper-Quiet Hunter Fan. 5-Year Limited Warranty.99.97% effective at removing particles as small as 0.3 Microns that pass through the filter. Overall airborne particle retention in any environment depends upon a number of factors including the amount of air processed the particle type and the rate of particle introduction into the environment.