30" X 20" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 32 5/8" X 22 5/8"] Aluminum Bar + Product Details Size – 4 X 12 Is CRFG2028 Width_14in

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

our Circular Air Supply Valves are ideal for low and medium pressure ventilation air conditioning systems

and Centralized Air Ducted Units

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Both lines taped together every 18in for easier handling & installation

30" X 20" Steel Return Air Filter Grille for 1" Filter Removable Frame [Outer Dimensions: 32 5 8" X 22 5 8"] Aluminum Bar + Product Details Size – 4 X 12 Is CRFG2028 Width_14in + Product Details Size – 18"w X 18"h is the size for the duct opening measurement only our Circular Air Supply Valves are ideal for low and medium pressure ventilation air conditioning systems