16" X 16" [Duct Opening] 4-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 17.75"W X 17.75"H] with filter + Product Details Size –

+ Product Details Size – 20"w X 6"h is the size for the duct opening measurement only

Think of the diameter as a straight line from one end to the other

+ Product Details Size – 26"w X 12"h is the size for the duct opening measurement only

+ Product Details Size - 36"w X 8"h is the size for the duct opening measurement only

16" X 16" [Duct Opening] 4-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 17.75"W X 17.75"H] with filter + Product Details Size –+ Product Details Size 16"w X 16"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 17. 75" width X 17. 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