GeneralAire 11-GA100A37 - 20" x 25" x 5" Replacement Filter for Honeywell FC100A1037, MERV 11, GFI #4368

Nominal Filter Dimensions: 20x25x5

Actual Filter Dimensions: 19-7/8" x 24-7/8" x 4-3/8"

Replace the filter every 6 months, depending on the environment may need to be replaced more often.