12" x 28" or 28" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter white Example: If your hole is 4 X 12 Is CRFG2028 Width_14in

Example: If your hole is 20" wide by 14" tall

+ Product Details Size – 36"w X 6"h is the size for the duct opening measurement only

+ Product Details Size – 25"w X 12"h is the size for the duct opening measurement only

+ Product Details Size - 32"w X 28"h is the size for the duct opening measurement only

this model allows for mounting without removing the thermostat

12" x 28" or 28" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter white Example: If your hole is 4 X 12 Is CRFG2028 Width_14in Example: If your hole is 20" wide by 14" tall + Product Details Size – 36"w X 6"h is the size for the duct opening measurement only