30" X 18" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 32 5/8" X 20 5/8"] Grilles Efficient Airflow Design: The slots

Efficient Airflow Design: The slots are meticulously angled to diversify airflow in two directions

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 24" OR 24" x 20" duct opening (measured at the opening)

Actual Filter Size – 24 3/4"w x 27 3/4" x 1"

Size - 10"w X 10"h is the size for the duct opening measurement only

Actual Filter Size – 31 3/4"w x 19 3/4" x 1"

30" X 18" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 32 5/8" X 20 5/8"] Grilles Efficient Airflow Design: The slots+ Product Details Size 30"w X 18"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 32 5 8" width X 20 5 8" height Actual Filter Size 29 3 4"w x 17 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.