12" X 4" [Duct Opening] 2-Way Horizontal Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 5.75"H] Compatible With Duct 10in + Product Details Size -

+ Product Details Size - 28"w X 8"h is the size for the duct opening measurement only

Actual Filter Size – 24 3/4"w x 21 3/4" x 1"

actual front end outer dimensions are approximately 34 5/8" width X 16 5/8" height

actual front end outer dimensions are approximately 38 5/8" width X 18 5/8" height -

12" X 4" [Duct Opening] 2-Way Horizontal Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 5.75"H] Compatible With Duct 10in + Product Details Size -+ Product Details Size 12"w X 4"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 13. 75" width X 5. 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