4" X 8" Or 8" X 4" Heavy Duty Floor Grille - Fixed Blades Air Grille - Brown [Outer Dimensions: 5.75 X 9.75] Outdoor Vent Covers Measuring 6" in diameter for

Measuring 6" in diameter for the duct opening

+ Product Details Size & Compatibility – The 6" Galvanized Sheet Metal 90 Degree Oval Vertical Angle Elbow is compatible with Duct 6"

+ Product Details Size & Compatibility – The 5" galvanized steel round side take-off is compatible with duct 5"

this fitting is perfectly compatible with 18-inch ducts

4" X 8" Or 8" X 4" Heavy Duty Floor Grille - Fixed Blades Air Grille - Brown [Outer Dimensions: 5.75 X 9.75] Outdoor Vent Covers Measuring 6" in diameter for+ Product Details Size 4"w X 8"h or 8" x 4" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 5. 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