3M Filtrete Allergen Defense Filter, 12-Inch by 12-Inch by 1-Inch 12x12x1 1000 MPR Electrostatic filter attracts and captures dust, pollen, dust-mite debris, mold spores, pet dander, smoke, smog, and bacteria Improves air quality by cleaning air with each pass through the filter Keeps your furnace or air conditioner running efficiently Outperforms comparable fiberglass and washable/reusable filters