12" X 6" [Duct Opening] 3-Way Air Vent Adjustable Aluminum Curved Blades Integral Multi-Shutter Damper HVAC Diffuser [Outer Dimensions: 13.75"W X 7.75"H] 8in diameter + Product Details Size -

+ Product Details Size - 20"w X 28"h is the size for the duct opening measurement only

12"w X 4"h Is The Size For The Duct Opening Measurement Only

+ Product Details Size - 14"w X 32"h is the size for the duct opening measurement only

Actual Filter Size – 21 3/4"w x 27 3/4" x 1"

12" X 6" [Duct Opening] 3-Way Air Vent Adjustable Aluminum Curved Blades Integral Multi-Shutter Damper HVAC Diffuser [Outer Dimensions: 13.75"W X 7.75"H] 8in diameter + Product Details Size -+ Product Details Size 12"w X 6"h is the size for the duct opening measurement only, actual front end outer dimensions are 13. 75" width X 7. 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