12" X 12" [Duct Opening] 1-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 13.75"H] Material_Aluminum and then smoothly drop in

and then smoothly drop in the grill

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

The installation process is a breeze

+ Product Details Size - 12"w X 36"h is the size for the duct opening measurement only

12" X 12" [Duct Opening] 1-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 13.75"H] Material_Aluminum and then smoothly drop in+ Product Details Size 12"w X 12"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 13. 75" width X 13. 75" height. High Quality High quality steel with counter sunk screw holes (screws included) and no sharp edges. Equipped with a lever for easy airflow adjustment and dampening. Airflow Control Adjustable airflow lever allows precise control over the direction and volume of air. Installation