14" X 14" [Duct Opening] 3-Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 15.75"W X 15.75"H] Compatible With Duct 12in + Product Details Size - 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size - 18"w X 34"h is the size for the duct opening measurement only

Ideal for Walls & Ceilings: Designed for seamless installation in standard 14" X 4" duct openings

also called T-Bar systems

+ Product Details Perfect Fit & Easy Sizing - Designed for a 24" x 24" duct opening (measured at the opening)

12" x 3" Decorative Wood Air Vent HVAC Duct Cover Grille - Polished Finish Red Oak Wood - 2-Way Air Direction

14" X 14" [Duct Opening] 3 Way Fixed Curved Blade Air Supply Diffuser Register Vent Cover Grille [Outer Dimensions: 15.75"W X 15.75"H] Compatible With Duct 12in + Product Details Size 4 X 12 Is CRFG2028 Width_14in + Product Details Size 18"w X 34"h is the size for the duct opening measurement only Ideal for Walls & Ceilings: Designed for seamless installation in standard 14" X 4" duct openings