Nominal: 20 x 24 x 1, size: 19 1/2"x23 1/2"x3/4" 20x24x1, ac furnace air filter comparable to 3m filtrete mpr 1000 to 1200 micro allergen defense comparable to honeywell allergen plus fpr 7 fights lint, dust mites, mold spores, pollen, pet dander, dust, and smoke. change frequency 60-90 days, made in the usa.
