20″ x 20″ x 1″, Gray, Basic Dust & Lint Reduction Filtrete Filter, Electrostatically Charged Fibers Attract & Capture Large Airborne Allergens Like Pollen, Household Dust & Lint, Ideal For High Velocity Heating/Cooling Systems, Performs Better Than Ordinary Fiberglass & Washable 1″ Filters, For Residential Use Only. MPR Rating 300, Filter Lasts For 90 Days.