Designed to fit Blueair 400 Classic Series Air Purifiers. Includes Blueair 402, Blueair 403, Blueair 405, Blueair 410, Blueair 450E, and Blueair 455EB. Filtration captures up to 99.97 percent of particles as small as 0.3 microns including smoke, dust, pollen, pet hair and dander, mold spores, and dust mites. Recommended to replace every six (6) months for maximum efficiency, or more often in harsh environments. Approximate Dimensions: 4 x 10 x 21 inches. Package contains two (2) replacement filter. Filter-Monster branded true replacement filter compatible with Blueair 400 Series Particle Filter removes smoke, dust, pollen, pet hair and dander, mold spores and dust mites from the air. Contains two (2) replacement filters.