8" X 4" [Duct Opening] 1-Way Air Vent Adjustable Aluminum Curved Blades Integral Multi-Shutter Damper HVAC Diffuser [Outer Dimensions: 9.75"W X 5.75"H] 18in diameter actual front end outer dimensions

actual front end outer dimensions are approximately 30 5/8" width X 18 5/8" height

+ Product Details Size - 30"w X 4"h is the size for the duct opening measurement only

Actual Filter Size – 35 3/4"w x 5 3/4" x 1"

with actual outer dimensions of 12

8" X 4" [Duct Opening] 1-Way Air Vent Adjustable Aluminum Curved Blades Integral Multi-Shutter Damper HVAC Diffuser [Outer Dimensions: 9.75"W X 5.75"H] 18in diameter actual front end outer dimensions+ Product Details Size 8"w X 4"h is the size for the duct opening measurement only, actual front end outer dimensions are 9. 75" width X 5. 75" height. Design Individually adjusting curved blades. Multi shutter damper with handle operator to adjust air flow. Screws Included High Quality Aluminum The premium durable aluminum will never rust and it will never wear through leaving the material with an elegant, beautiful, and smooth surface, adds a