Nordic Pure 12x24x4M13-1 12x24x4 MERV 13 Pleated AC Furnace Air Filter, Box of 1, 4-Inch Actual Size of Air Filter: 11 1/2 x 23 3/8 x 3 5/8 (11.5 x 23.38 x 3.63) inches MERV 13 is comparable to MPR 2200, 2400, and FPR 10 All Nordic Pure air filters are electrostatically charged for maximum performance Attracts and captures dust, lint, pollen, bacteria, pet dander, dust mites, mold spores, smoke particles, smog, viruses, coughs and sneezes Made in the USA