8" X 6" [Duct Opening] 3-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 9.75"H X 7.75"H] 18" Round Duct Pipe + Product Details Size -

+ Product Details Size - 25"w X 36"h is the size for the duct opening measurement only

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these heavy-duty louvers are ideal for use in attics

+ Product Details Size – 10"w X 12"h is the size for the duct opening measurement only

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8" X 6" [Duct Opening] 3-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 9.75"H X 7.75"H] 18" Round Duct Pipe + Product Details Size -+ Product Details Size 8"w X 6"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 9. 75" width X 7. 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 Location