Filtrete 2 Pack 20"x25"x1" Micro Allergen Reduction Filter. Outperforms fiberglass, washable, and non-electrostatic filters. Designed with exclusive Filtrete Brand 3-in-1 technology from 3M, it traps unwanted air particles while letting cleaner air flow through. Attracts and captures particles such as lint, pollen, dust, pet dander, smoke, and smog. The higher the MPR, the more microparticles your filter will capture from the air passing through it. For optimal performance of your heating & cooling system or HVAC system, change your home air filter at least every 90 days for 1 inch filters, and at least every 12 months for 4 inch and 5 inch filters harder to keep you warm or cool-wasting energy. For Residential use only. Create a change countdown in the Filtrete Smart app.