Aerostar 21 1/4x21 1/4x1 MERV 13, 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 1500 to 1900 Ultimate Allergen Defense Comparable to Honeywell Allergen Elite FPR 10 Fights lint, dust mites, mold spores, pollen, pet dander, fine dust, smoke, viruses, and bacteria. Change frequency 60-90 days, Made in the USA.