Healthy Air 18x18x1 MERV 8 Pleated Furnace Air Filter, Box of 6 Actual Size of Filter: 17 1/2 x 17 1/2 x 3/4 Hypoallergenic and antimicrobial pleated electrostatic filter material Comparable to a MPR rating of 500 - 600 Superior Air Filter for Residential or Commercial Property Made in the USA