28" X 26" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 30 5/8" X 28 5/8"] w12h12 and the second number represents

and the second number represents the height

+ Product Details Size - 26"w X 20"h is the size for the duct opening measurement only

Noise free components - no vibrating louvers etc

Actual Filter Size – 33 3/4"w x 11 3/4" x 1"

or luxury Victorian design

28" X 26" Steel Return Air Filter Grille for 1" Filter - Removable Frame - [Outer Dimensions: 30 5/8" X 28 5/8"] w12h12 and the second number represents+ Product Details Size 28"w X 26"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 30 5 8" width X 28 5 8" height Actual Filter Size 27 3 4"w x 25 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.