Filtrete 18x20x1 AC Furnace Air Filter MPR 1000 Micro Allergen Defense 4-Pack.... OUTPERFORMS FIBERGLASS, WASHABLE AND NON-ELECTROSTATIC 3-month pleated 1 in. home air filters for your furnace, air conditioner or HVAC system DESIGNED WITH EXCLUSIVE Filtrete Brand 3-in-1 technology from 3M to trap 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--such as pollen, pet dander, smoke, bacteria and viruses--your filter will capture from the air passing through it