8" Circular Round Aluminum HVAC Supply Grille Air Diffuser - With Butterfly Damper - Vent Duct Cover [Outer Dimensions: 10"] w16h16 + Product Details Size - 4 X 12 Is CRFG2028 Width_14in

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

+ Product Details Size - 6"w X 4"h is the size for the duct opening measurement only

+ Product Details Size – 10" x 16" or 16" x 10" is the size for the duct opening measurement only

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

actual front end outer dimensions are approximately 22 5/8" width X 26 5/8" height

8" Circular Round Aluminum HVAC Supply Grille Air Diffuser With Butterfly Damper Vent Duct Cover [Outer Dimensions: 10"] w16h16 + Product Details Size 4 X 12 Is CRFG2028 Width_14in + Product Details Size 28"w X 28"h is the size for the duct opening measurement only + Product Details Size 6"w X 4"h is the size for the duct opening measurement only