12" X 16" or 16" X 12" Heavy Duty Floor Grille - Fixed Blades Air Grille - Brown [Outer Dimensions: 13.75 X 17.75] w34h34 + Product Details Size -

+ Product Details Size - 12"w X 18"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 36 5/8" width X 16 5/8" height

Electrical Connections: Turn off the main power supply before making any electrical connections

+ Product Details Size – Sheet metal duct board take off start collar is 12" and it is compatible with duct 12"

And The Full Outer Portion Is Double Layered

12" X 16" or 16" X 12" Heavy Duty Floor Grille - Fixed Blades Air Grille - Brown [Outer Dimensions: 13.75 X 17.75] w34h34 + Product Details Size -+ Product Details Size 12"w X 16"h or 16" X 12" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 13. 75" width X 17. 75" height. High Quality High grade steel construction meant for high foot traffic areas. Installation Location Floor. Design Easy drop in installation. Powder Coat Finish Smooth, shiny, scratch resistant, with no sharp edges. Looks like it was just waxed. Quality Packaging Carefully