12"w X 12"h [Duct Opening] 3-Way Horizontal Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 13.75"H] Compatible with Duct 8" + Product Details Size –

+ Product Details Size – 25"w X 36"h is the size for the duct opening measurement only

Actual Filter Size – 17 3/4"w x 7 3/4" x 1"

+ Product Details Perfect Fit & Easy Sizing - Designed for a 30" x 12" OR 12" x 30" duct opening (measured at the opening)

actual front end outer dimensions are approximately 18

The ring base allows installation without removing the thermostat

12"w X 12"h [Duct Opening] 3-Way Horizontal Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 13.75"H] Compatible with Duct 8" + 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