18x30x1 AC and Furnace Air Filter by Aerostar - MERV 11, Box of 6

Nominal Size: 18 x 20 x 1, Actual Size: 17 1/2" x 29 1/2" x 3/4" 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.