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] Curved Blade Steel + Product Details Size –

+ Product Details Size – 20"w X 26"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 26 5/8" width X 24 5/8" height

+ Product Details Size - 18"w X 20"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 36 5/8" width X 28 5/8" height

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] Curved Blade Steel + 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