This is a compatible replacement filter for the Honeywell FC40R1094 return grille filter. It has a MERV 10 efficiency and captures small indoor air particles like pollen, pet dander and dust.
Nominal size: 12x12x4-3/8
Actual size (with header): 11-3/4 x 11-3/4 x 4-3/8
Also known as FC40R-1094.