Filtrete 20x25x4 MPR 1000 Air Filter, made by 3M, helps capture unwanted particles from your household air to contribute to a cleaner, fresher home environment. Designed with exclusive Filtrete 3-in-1 technology, including an MPR 1000 and MERV 11 rating, your AC filter will help pull and capture countless microparticles – such as pet dander, smoke and smog – while letting cleaner air flow through. Your Filtrete Filter will also capture large particles, including lint, pollen, mold spores and household dust. Use a 12-month 4-inch home HVAC filter in your furnace, air conditioner or HVAC system. For optimal performance of your heating and cooling system or HVAC system, change your 4-inch furnace filter at least once per year. Fits systems calling for a filter thickness of 4.31" and larger. Filtrete Brand is North America’s most trusted brand of HVAC Filters (1).