Eco-Aire 20x20x4 MERV 11, Pleated Air Filter, 20x20x4, Box of 6, Made in the USA Nominal: 20x20x4 or (20 x 20 x 4), Size: 19 1/2"x19 1/2"x3 3/4", AC Furnace Air Filter Made in the USA Designed to last up to 60 Days Comparable to 3M Filtrete Ultra Allergen: Filtrete 1250 Captures airborne particles between 1 and 10 microns in size