25" X 16" Steel Return Air Filter Grille for 1" Filter - Fixed Hinged - [Outer Dimensions: 27 5/8" X 18 5/8"] w34h34 + Product Details Size - 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size - 30"w X 4"h is the size for the duct opening measurement only

Adjustable airflow control - by rotating the middle disk

+ Product Description Maximize HVAC efficiency with our aluminum eggcrate return air filter grille

and extends HVAC system life

actual front end outer dimensions are approximately 26 5/8" width X 18 5/8" height

25" X 16" Steel Return Air Filter Grille for 1" Filter Fixed Hinged [Outer Dimensions: 27 5 8" X 18 5 8"] w34h34 + Product Details Size 4 X 12 Is CRFG2028 Width_14in + Product Details Size 30"w X 4"h is the size for the duct opening measurement only Adjustable airflow control by rotating the middle disk