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 these heavy-duty louvers are ideal

these heavy-duty louvers are ideal for use in attics

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Actual Filter Size – 29 3/4"w x 29 3/4" x 1"

with actual outer dimensions of 16

+ 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 these heavy-duty louvers are ideal+ 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.