12"w X 6"h [Duct Opening] 2-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 7.75"H] 12" Round Duct Pipe and with a built-in back

and with a built-in back 1/2" mesh they also protect you from annoying rodents like mice

Actual Filter Size – 11 3/4"w x 23 3/4" x 1"

Actual Filter Size – 33 3/4"w x 15 3/4" x 1"

Actual Filter Size – 33 3/4"w x 7 3/4" x 1"

12"w X 6"h [Duct Opening] 2-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 13.75"W X 7.75"H] 12" Round Duct Pipe and with a built-in back+ Product Details Size 12"w X 6"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 13. 75" width X 7. 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