18"w X 8"h Aluminum Adjustable Return/Supply HVAC Air Grille Fixed Blades with Damper + Product Details Size –

+ Product Details Size – 6" x 16" or 16" x 6" is the size for the duct opening measurement only

+ Product Details Size – 12"w X 4"h is the size for the duct opening measurement only

and Diffusers

+ Product Details Size - 8"w X 16"h is the size for the duct opening measurement only

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18"w X 8"h Aluminum Adjustable Return/Supply HVAC Air Grille Fixed Blades with Damper + Product Details Size –+ Product Details Size 18"w X 8"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 19. 85" width X 9. 85" height. High Quality Rigid aluminum construction with counter sunk screw holes (screws included) and no sharp edges. Installation Location Sidewall and ceiling. Design Unrestricted airflow for your HVAC system adjustable one way louver with full horizontal airflow directional control single