28" X 20" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 30 5/8" X 22 5/8"] 8in diameter + Product Details Size – 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size – 10"w X 36"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 12 5/8" width X 26 5/8" height

actual front end outer dimensions are approximately 28 5/8" width X 8 5/8" height

+ Product Details Size - The listed 6" diameter refers specifically to the size of the duct opening

+ Product Details Size – 28"w X 18"h is the size for the duct opening measurement only

28" X 20" Steel Return Air Filter Grille for 1" Filter Removable Frame [Outer Dimensions: 30 5 8" X 22 5 8"] 8in diameter + Product Details Size – 4 X 12 Is CRFG2028 Width_14in + Product Details Size – 10"w X 36"h is the size for the duct opening measurement only actual front end outer dimensions are approximately 12 5 8" width X 26 5 8" height