Accumulair Platinum 20x23x1 (Actual Size) MERV 11 Air Filter/Furnace Filters (4 pack) Actual size measures 20 x 23 x 0.75 Merv 11 rating Each filter lasts up to 3 months Supercharged pleated panel filtering media ideally suited for capturing fine airborne allergens such as dust, smoke, dander Buy one year of filters in one purchase ( each filter lasts 3 months under normal use)