Tier1 Replacement for Lennox 20x26x5 Merv 11 AC Furnace Air Filter 2 Pack Captures 90% of harmful airborne particles such as dus, pollen, pet dander, mold spores, smog, & more Comparable Filter Replacement For: Lennox X0587, ABC2000, FR2000, BMAC20-CE Actula Size: 20 inches (length) x 25 7/8 inches (width) x 4 7/8 inches (thickness) Original box type design Recommend filter life of 3 months to reduce damage to your furnace / ac unit