18" X 12" Steel Return Air Filter Grille for 1" Filter - Removable Frame - * Filter Included * [Outer Dimensions: 20 5/8" X 14 5/8"] Brown with actual outer dimensions of

with actual outer dimensions of 16

The back is completely insulated

+ Product Details Size – 28"w X 8"h is the size for the duct opening measurement only

you have 16 different varieties to choose from

+ Product Spec Sheet

18" X 12" Steel Return Air Filter Grille for 1" Filter - Removable Frame - * Filter Included * [Outer Dimensions: 20 5/8" X 14 5/8"] Brown with actual outer dimensions of+ Product Details Size 18"w X 12"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 20 5 8" width X 14 5 8" height Actual Filter Size 17 3 4"w x 11 3 4" x 1" High Quality High quality solid stamped steel with counter sunk screw holes (screws included) and no sharp edges Installation Location Sidewall and ceiling Design Removable door face for easy filter change & cleaning uses a 1" thick filter.