This is a compatible replacement return grille filter for Honeywell FC40R1136. It has a MERV 10 efficiency rating and has a nominal size of 18x24x4-3/8.
Nominal size: 18x24x4-3/8
Actual size (without header): 16-1/4 x 22-1/4 x 4-3/8
Actual size (with header): 17-3/4 x 23-3/4 x 4-3/8
The Magnet logo on this page signifies that this product is a factory direct replacement to the OEM branded filter.