Lennox X6673 MERV 11 Filter Media (5 Pack) 98% efficient filtration media capturing particles as small as 0.3 microns before they can collect on your coils High-efficiency alternative to one-inch filters Fits the X6660 HCC20-28 Air Cleaner Filter dimensions: 20" x 25" x 5" (actual: 19-7/8" x 24-3/4" x 4-3/8") Genuine Lennox OEM Furnace Filter