Actual Size: 13-1/2 x 23-1/2 x 7/8 Nominal Size: 14x24x1 Filtration Rating: MERV 10. Comparable to MPR rating 600 to 800, or FPR 5-6 rating. Blocks and Captures: Dust, pollen, mold spores, pet dander, smog, dust mites, debris.