14" X 24" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 16 5/8" X 26 5/8"] w26h26 Think of the diameter as

Think of the diameter as a straight line from one end to the other

+ Product Details Size - 14"w X 20"h is the size for the duct opening measurement only

+ Product Details Size - 10"w X 12"h is the size for the duct opening measurement only

This grille is ideal for both sidewall and ceiling installations

with actual outer dimensions of 16

14" X 24" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 16 5/8" X 26 5/8"] w26h26 Think of the diameter as+ Product Details Size 14"w X 24"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 16 5 8" width X 26 5 8" height Actual Filter Size 13 3 4"w x 23 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.