30" X 30" Steel Return Air Filter Grille for 1" Filter - Fixed Hinged- [Outer Dimensions: 32 5/8" X 32 5/8"] Color_Black + Product Details Size - 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size - 12"w X 30"h is the size for the duct opening measurement only

+ Product Details Size - 20"w X 24"h is the size for the duct opening measurement only

+ Product Details Size - 36"w X 26"h is the size for the duct opening measurement only

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

[Outer Dimensions: 14

30" X 30" Steel Return Air Filter Grille for 1" Filter Fixed Hinged [Outer Dimensions: 32 5 8" X 32 5 8"] Color_Black + Product Details Size 4 X 12 Is CRFG2028 Width_14in + Product Details Size 12"w X 30"h is the size for the duct opening measurement only + Product Details Size 20"w X 24"h is the size for the duct opening measurement only