10"w X 10"h [Duct Opening] 4-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 11.75"W X 11.75"H] w30h30 + Product Details Size -

+ Product Details Size - 30"w X 4"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 12 5/8" width X 20 5/8" height

+ Product Details Size - 20"w X 30"h is the size for the duct opening measurement only

For 12" Round Duct Opening - Spiral or Flex

10"w X 10"h [Duct Opening] 4-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 11.75"W X 11.75"H] w30h30 + Product Details Size -+ Product Details Size 10"w X 10"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 11. 75" width X 11. 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