This return grille filter is a compatible replacement for the Honeywell FC40R1185. It has a MERV 10 efficiency and measures approximately 18 x 18 x 4-3/8.
Nominal Size: 18x18x4-3/8
Actual Size (without header): 16-1/4 x 16-1/4 x 4-3/8
Actual Size (with header): 17-3/4 x 17-3/4 x 4-3/8
The Magnet logo on this page signifies that this product is a factory direct replacement to the OEM branded filter.