20"W X 8"H [Duct Opening] ALUMINUM RETURN GRILLE - EASY AIR FLOW - LINEAR BAR GRILLES [OUTER DIMENSIONS: 19.875"W X 9.875"H] 12" Round Duct Pipe + Product Details Perfect Fit 4 X 12 Is CRFG2028 Width_14in

+ Product Details Perfect Fit & Easy Sizing - Designed for a 14" x 18" OR 18" X 14" duct opening (measured at the opening)

while the included safety wire provides added security to prevent the door from falling off

actual front end outer dimensions are approximately 27 5/8" width X 20 5/8" height

+ Product Details Size - 34"w X 8"h is the size for the duct opening measurement only

14" Circular Round Aluminum HVAC Supply Grille Air Diffuser - With Butterfly Damper - Vent Duct Cover

20"W X 8"H [Duct Opening] ALUMINUM RETURN GRILLE EASY AIR FLOW LINEAR BAR GRILLES [OUTER DIMENSIONS: 19.875"W X 9.875"H] 12" Round Duct Pipe + Product Details Perfect Fit 4 X 12 Is CRFG2028 Width_14in + Product Details Perfect Fit & Easy Sizing Designed for a 14" x 18" OR 18" X 14" duct opening (measured at the opening) while the included safety wire provides added security to prevent the door from falling off