12"W X 12"H [Duct Opening] Steel Air Vent Return Grille - HVAC VENT DUCT COVER DIFFUSER - [Outer Dimensions: 13.75"W X 13.75"H] 18" Round Duct Pipe and waste gases transmission lines

and waste gases transmission lines

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And Meets/Beats ASTM B280 Standard

It has an outer surface made of high-quality aluminum foil and an inner surface made of metalized PET with inside high-tensile spring steel wire

12"W X 12"H [Duct Opening] Steel Air Vent Return Grille - HVAC VENT DUCT COVER DIFFUSER - [Outer Dimensions: 13.75"W X 13.75"H] 18" Round Duct Pipe and waste gases transmission lines+ 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. Design Easy unrestricted airflow for your HVAC system 50 angled to provide maximum airflow. High Quality Solid stamped steel with counter sunk screw holes (screws included) and no sharp edges. Powder Coat Finish Smooth, shiny, scratch resistant, beautiful. Looks like it was just