Filtrete 9849 Micro Allergen Reduction Filters, 1000 MPR, 12 x 18 x 1, 6-Pack Microparticle Performance Rating of 1,000 Captures large airborne allergens like household dust, pollen, and mold spores Attracts and captures microscopic allergens like pet dander, smoke, and smog particles Attracts and captures microscopic allergens like pet dander, smoke, and smog particles Outperforms non-electrostatic filters, Lasts up to 3 months Keeps your furnace or air conditioner running efficiently, Pack of 6 filters