20x20x5 (19.75x19.75x4.38) MERV 13 Aftermarket Honeywell Replacement Filter (2 Pack) Honeywell model FC40R air filter # FC40R1003. Replaces Expandapac filter # FC35A1043 that was used in model F35R1002. Aftermarket replacement filter. Nominal size 20 x 20 x 5. Actual size 19 3/4 x 19 3/4 x 4 3/8. This is an aftermarket filter.