Aerostar 21 1/4x21 1/4x1 MERV 8, Pleated Air Filter, 21 1/4 x 21 1/4 x 1, Box of 6, Made in the USA

Nominal: 21 1/4 x 21 1/4 x 1, Size: 21 1/4"x21 1/4"x3/4" 21 1/4x21 1/4x1, AC Furnace Air Filter Comparable to 3M Filtrete MPR 600 Clean Living Comparable to Honeywell Micro Defense Plus FPR 5 Fights lint, dust mites, mold spores, pollen, pet dander, and dust. Change frequency 60-90 days, Made in the USA.