12" X 12" [Duct Opening] 2-Way Horizontal Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 13.75"H] w36h36 + Product Details Size - 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size - 25"w X 16"h is the size for the duct opening measurement only

10"w X 4"h Is The Size For The Duct Opening Measurement Only

+ Product Details Size – 16"w X 30"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 34 5/8" width X 26 5/8" height

+ Product Details Size - 16"w X 14"h is the size for the duct opening measurement only

12" X 12" [Duct Opening] 2 Way Horizontal Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 13.75"H] w36h36 + Product Details Size 4 X 12 Is CRFG2028 Width_14in + Product Details Size 25"w X 16"h is the size for the duct opening measurement only 10"w X 4"h Is The Size For The Duct Opening Measurement Only