21.5x27.5x5 (21.25x27.25x4.38) MERV 13 Aftermarket Honeywell Replacement Filter (2 Pack) Honeywell F27F and F100 Media Air Filter # FC100A1045. Nominal size 21.5 x 27.5 x 5. Actual size 21 1/4 x 27 1/4 x 4 3/8. Package contains 2 Filters. This is an aftermarket filter.