12" X 12" Steel Return Air Filter Grille for 1" Filter - Removable Frame - * Filter Included *[Outer Dimensions: 14 5/8" X 14 5/8"] 18in diameter + Product Details Size –

+ Product Details Size – 20"w X 34"h is the size for the duct opening measurement only

Design – Cubic core eggcrate design Offers highest airflow efficiency at almost 95%

+ Product Details Size – 18"w X 30"h is the size for the duct opening measurement only

Actual Filter Size – 23 3/4"w x 13 3/4" x 1"

12" X 12" Steel Return Air Filter Grille for 1" Filter - Removable Frame - * Filter Included *[Outer Dimensions: 14 5/8" X 14 5/8"] 18in diameter + Product Details Size –+ Product Details Size 12"w X 12"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 14 5 8" width X 14 5 8" height Actual Filter Size 11 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.