Eco-Aire 18x28x1 MERV 13, Pleated Air Filter, 18x28x1, Box of 6, Made in the USA Nominal: 18x28x1 or (18 x 28 x 1), Size: 18"x28"x1", AC Furnace Air Filter Made in the USA Designed to last up to 60 Days Comparable to the 3M Filtrete Dust and Pollen: Filtrete 2000 Captures airborne particles less than 1 micron in size