The Honeywell FC40R1185 fits the following:
The Honeywell FC40R1185 Return Air Grille Filter 18x18 is a replacement air filter that mounts in most return filter grilles. The Honeywell return air grille filter features four inches of depth, which provides a higher efficiency than standard one inch filters. Featuring a MERV 10 rating, this Honeywell grille filter reduces particulates in your air.
Honeywell FC40R1185 Return Air Grille Filter 18x18 specifications: