21 1/2 x 23 5/16 x 1 Carrier Replacement Filter by Aerostar - MERV 11, Box of 6

Nominal Size: 21-1/2 x 23-5/16 x 1, Actual Size: 21-1/2" x 23-5/16" 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.