12" X 12" [Duct Opening] 4-Way Air Vent Adjustable Aluminum Curved Blades Integral Multi-Shutter Damper HVAC Diffuser [Outer Dimensions: 13.75"W X 13.75"H] Fixed Blades with Damper + Product Details Size -

+ Product Details Size - 36"w X 12"h X 2"d (for duct opening measurement only)

+ Product Details Size – 12"w X 10"h is the size for the duct opening measurement only

+ Product Details Size – 18"w X 25"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 18" x 18" duct opening (measured at the opening)

12" X 12" [Duct Opening] 4-Way Air Vent Adjustable Aluminum Curved Blades Integral Multi-Shutter Damper HVAC Diffuser [Outer Dimensions: 13.75"W X 13.75"H] Fixed Blades with Damper + Product Details Size -+ Product Details Size 12"w X 12"h is the size for the duct opening measurement only, actual front end outer dimensions are 13. 75" width X 13. 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