Filter-Monster True HEPA Replacement suitable with Bissell 2521 Filter for air400 Air Purifiers, 3 Pack

Dimensions: 15.75 x 13.38 x 1.38 inches each.. Package contains (3) HEPA filters with (3) attached pre-filters. Recommended to replace HEPA and pre-filter every 6 months for maximum efficiency, or more often depending on air superior and environmental factors. True HEPA filter captures up to 99.97 percent of airborne particles as small as 0.3 microns in size including smoke, dust, pollen, pet hair and dander, mold spores and dust mites. Also removes harmful VOCs and household odors from cooking, cleaning, smoking and pets. Pre-filter acts as first layer of filtration to capture larger particles before reaching HEPA filter. Engineered to fit Bissell air400 air purifier, series 24791. Replacement appropriate with Bissell 2521 filter