Actual Size: 11-1/2 x 11-1/2 x 1-3/4 Nominal Size: 12x12x2 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.