18"W X 14"H [Duct Opening] Steel Air Vent Return Grille - HVAC VENT DUCT COVER DIFFUSER - [Outer Dimensions: 19.75"W X 15.75"H] White + Product Details Size – 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size – 8" x 16" or 16" x 8" is the size for the duct opening measurement only

The 1/2" black insulation

+ Product Details Size - 10"w X 36"h is the size for the duct opening measurement only

+ Product Details Size - 24"w X 34"h is the size for the duct opening measurement only

+ Product Details Size - 24"w X 24"h is the size for the duct opening measurement only

18"W X 14"H [Duct Opening] Steel Air Vent Return Grille HVAC VENT DUCT COVER DIFFUSER [Outer Dimensions: 19.75"W X 15.75"H] White + Product Details Size – 4 X 12 Is CRFG2028 Width_14in + Product Details Size – 8" x 16" or 16" x 8" is the size for the duct opening measurement only The 1 2" black insulation