10" X 30" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 12 5/8" X 32 5/8"] Fixed Blades with Damper + Product Details Size - 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size - 18"w X 32"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

+ Product Details Size - 30"w X 6"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 22 5/8" width X 8 5/8" height

Some of the best features aren't readily apparent

10" X 30" Steel Return Air Filter Grille for 1" Filter Removable Frame [Outer Dimensions: 12 5 8" X 32 5 8"] Fixed Blades with Damper + Product Details Size 4 X 12 Is CRFG2028 Width_14in + Product Details Size 18"w X 32"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