8" X 8" Heavy Duty Floor Grille - Fixed Blades Air Grille - Brown [Outer Dimensions: 9.75 X 9.75] Compatible with Duct 4" + Product Details Size –

+ Product Details Size – 16"w X 36"h is the size for the duct opening measurement only

See our separate listing for Butterfly Dmaper to Control Airflow

Actual Front End Outer Dimensions Are 10" Diameter

+ Product Details Size - 18"w X 12"h X 2"d (for duct opening measurement only)

8" X 8" Heavy Duty Floor Grille - Fixed Blades Air Grille - Brown [Outer Dimensions: 9.75 X 9.75] Compatible with Duct 4" + Product Details Size –+ Product Details Size 8"w X 8"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 9. 75" width X 9. 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 shrink wrapped