12" X 18" Steel Return Air Filter Grille for 1" Filter - Fixed Hinged - [Outer Dimensions: 14 5/8" X 20 5/8"] Insulated Line + Product Details Size -

+ Product Details Size - 28"w X 36"h is the size for the duct opening measurement only

the second number represents the height

+ Product Details Size - 20"w X 16"h is the size for the duct opening measurement only

The 1/2" black insulation

12" X 18" Steel Return Air Filter Grille for 1" Filter - Fixed Hinged - [Outer Dimensions: 14 5/8" X 20 5/8"] Insulated Line + Product Details Size -+ Product Details Size 12"w X 18"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 14 5 8" width X 20 5 8" height. High Quality high quality solid stamped steel with counter sunk screw holes (screws included) and no sharp edges Installation Location Ceiling Design Fixed hinged for easy filter change & cleaning uses a 1" thick filter. Our filter grille latch is easy to use on your fingers and