High Performance Filter Contains 1 Filter Lasts Up To 3 Months 1900 Performance Rating Filtrete&Reg; Ultimate Allergen Reduction Filters Provide An Easy Way To Help Reduce Airborne Allergens In Your Home. They Capture Large Airborne Particles From The Air That Passes Through Them, Including Dust, Pollen, And Mold Spores. They Also Trap Microscopic Allergens, Such As Pet Dander, Smoke, Smog, And Particles That Can Carry Bacteria, Viruses And Odors. The Difference Is In The Microparticle Performance Rating (Mpr) And Air Flow Balance. How We Measure Filtrete Filter Performance: Filtrete Air Cleaning Filters Are Electrostatically Charged To Attract And Capture Particles From The Air That Passes Through The Filter. Each Filtrete Filter Has A Microparticle Performance Rating (Mpr). This Rating Measures A Filter's Ability To Capture Particles Between 0.3 And 1.0 Microns. The Higher The Mpr, The More Efficient The Filter Is At Capturing These Tiny Particles. How Clean Is Your Indoor Air And Water? Many People Would Be Surprised To Learn That The U.S. Environmental Protection Agency Says That Indoor Air Can Be Two To Five Times Worse Than The Air Outside. In Fact, The Epa Identifies Indoor Air Contamination As One Of The Top Five Environmental Risks To Public Health. Air And Water Quality Can Vary According To A Number Of Factors. For Example, Today's Energy-Efficient Homes Provide Better Insulation Than Ever Before, But Often At The Expense Of Air Exchange. As A Result, Moisture May Build Up, Creating A Breeding Ground For Things Like Bacteria, Fungi, And Mold. And Even The Best Municipal Water Systems Can Fail To Remove Chlorine Taste And Odor, As Well As Sediment And Parasitic Cysts In Drinking Water. Filtrete™ Home Filtration Products Empower You To Help Improve Your Indoor Air And Water Quality. We Are Making A Difference In Maintaining Healthier Home Environments.