12"w X 12"h [Duct Opening] 4-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 13.75"H] Compatible With Duct 10in + Product Details Size -

+ Product Details Size - 30"w X 18"h is the size for the duct opening measurement only

+ Product Details Size – 16"w X 36"h is the size for the duct opening measurement only

And The Cooler Air From Outside WIll Flow In From The Bottom

High Quality – high-quality steel with counter-sunk screw holes (screws included) and no sharp edges

12"w X 12"h [Duct Opening] 4-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 13.75"H] Compatible With Duct 10in + Product Details Size -+ Product Details Size 12"w X 12"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 13. 75" width X 13. 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