14" X 14" [Duct Opening] 3-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 15.75"W X 15.75"H] 8" Diameter + Product Details Size -

+ Product Details Size - 28"w X 20"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 38 5/8" width X 12 5/8" height -

+ Product Details Size – 6" round duct opening-

Looks like it was just waxed

+ Product Details Size - 12"w X 4"h is the size for the duct opening measurement only

14" X 14" [Duct Opening] 3-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 15.75"W X 15.75"H] 8" Diameter + Product Details Size -+ Product Details Size 14"w X 14"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 15. 75" width X 15. 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