6" x 28" or 28" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 30.5"] w20h20 + Product Details Size - 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size - 28"w X 28"h is the size for the duct opening measurement only

Actual Filter Size – 23 3/4"w x 33 3/4" x 1"

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

actual front end outer dimensions are approximately 14 5/8" width X 22 5/8" height

Looks Like It Was Just Waxed

6" x 28" or 28" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Aluminum White [Outer Dimensions: 8.5" X 30.5"] w20h20 + Product Details Size 4 X 12 Is CRFG2028 Width_14in + Product Details Size 28"w X 28"h is the size for the duct opening measurement only Actual Filter Size – 23 3 4"w x 33 3 4" x 1"