Tier1 Replacement for 21-1/2x23-1/2x1 Merv 8 Pleated Dust & Pollen AC Furnace Air Filter 6 Pack Similar to the 3M Filtrete Dust & Pollen 21-1/2x23-1/2x1 Air Filter Made in the U.S.A. Actual Size: 21 1/2 Inches (Length) x 23 1/2 Inches (Width) x 3/4 Inches (Thickness) Electrostatically-charged, pleated fabric filter media 3 Month Filter Life