DESC: The RabbitAir Bio Fresh Air Purifier uses a 3-stage filtration process to ELIMINATE, REMOVE and DESTROY many allergens, odors and germs. The 1st stage is the pre-filter (sink washable/dishwasher safe, no replacement) which captures large size particles, dust, pet hair, germs, fungus and mold. The 2nd stage is the BioGP® HEPA filter (lasts up to 3 years at 12 hours/day operation) which uses NEW! Bio Fibers that destroy bacteria and allergens ON the filter + Flu Prevention Coating! Conventional HEPA purifiers allow for bacteria growth and the result is an ineffective filter that lasts only a few months before needing replacement. The BioGP® HEPA filter destroys allergy germs, pollen, dust mites, bacteria, cigarette odor, fungus, greenhouse gasses, and many household odors.