US Home Filter SC40-12X24X4 MERV 8 Pleated Air Filter (3 Pack), 12" x 24" x 4" Actual size: 11-3/8" x 23-3/8" x 1-3/4" Merv 8 tested under ashram 52.2-2007 standards Ideal for normal air filtration and those with mild allergies Moisture resistant, heavy-duty frame Galvanized expanded metal backing