Accumulair Platinum 20x21.5x1 (Actual Size) MERV 11 Air Filter/Furnace Filters (6 pack) Actual size measures 20 x 21.5 x 0.75 Each filter lasts up to 3 months Uniform pleat shape enhances dust holding capacity and maximizes air flow Supercharged pleated panel filtering media ideally suited for capturing fine airborne allergens such as dust, smoke, dander Merv 11 rating