30" X 12" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 32 5/8" X 14 5/8"] Powder Coated actual front end outer dimensions

actual front end outer dimensions are approximately 18 5/8" width X 26 5/8" height

you can watch this informative video tutorial: How to Measure Your Vent Hole Before Ordering a Grille

If your duct opening is 14 inches in diameter

actual front end outer dimensions are approximately 16 5/8" width X 26 5/8" height -

30" X 12" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 32 5/8" X 14 5/8"] Powder Coated actual front end outer dimensions+ Product Details Size 30"w X 12"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 32 5 8" width X 14 5 8" height Actual Filter Size 29 3 4"w x 11 3 4" x 1" High Quality High quality solid stamped steel with counter sunk screw holes (screws included) and no sharp edges Installation Location Sidewall and ceiling Design Removable door face for easy filter change & cleaning uses a 1" thick filter.