Accumulair Emerald 20x30x2 (19.5x29.5x1.75) MERV 6 Air Filter/Furnace Filters (4 pack) Nominal size is 20x30x2. Actual size is 19.5 x 29.5 x 1.75. MERV 6 Rating. Each filter lasts up to 3 months. Economical, high-capacity media makes this filter an ideal upgrade from standard fiberglass throwaways. Captures a wide variety of airborne allergens including dust, mold, pet dander, and dust mites. 4 Pack of Air Filters