24" X 18" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 26 5/8" X 20 5/8"] Insulated Line Set + Product Details Size -

+ Product Details Size - 40"w X 20"h is the size for the duct opening measurement only

5" - SEE BELOW IN DESCRIPTION HOW TO MEASURE A GRILLE

improves airflow

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+ Product Spec Sheet

24" X 18" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 26 5/8" X 20 5/8"] Insulated Line Set + Product Details Size -+ Product Details Size 24"w X 18"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 26 5 8" width X 20 5 8" height Actual Filter Size 19 3 4"w x 19 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.