Tier1 Replacement for Lennox 20x25x5 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 X0586, X5426, X6661, X6673, X6675, X8304, X8307, X7751 Actual Size: 19 7/8 inches (length) x 24 3/4 inches (width) x 4 3/8 inches (thickness) Original box type design Recommend filter life of 3 months to reduce damage to your furnace / ac unit