32"W X 25"H [Duct Opening] Steel Air Vent Return Grille - HVAC VENT DUCT COVER DIFFUSER - [Outer Dimensions: 33.75"W X 26.75"H] w8h8 + Product Details Size - 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size - 36"w X 30"h is the size for the duct opening measurement only

+ Product Spec Sheet Corner Baseboard Grille Spec Sheet

so you are not left with much waste

+ Product Details Size - 32"w X 10"h is the size for the duct opening measurement only

High Quality – High-quality aluminum with counter-sunk screw holes (screws included) and no sharp edges

32"W X 25"H [Duct Opening] Steel Air Vent Return Grille HVAC VENT DUCT COVER DIFFUSER [Outer Dimensions: 33.75"W X 26.75"H] w8h8 + Product Details Size 4 X 12 Is CRFG2028 Width_14in + Product Details Size 36"w X 30"h is the size for the duct opening measurement only + Product Spec Sheet Corner Baseboard Grille Spec Sheet