8" x 12" or 12" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 14.5"] w12h12 + Product Details Size - 7" Round Duct Pipe Quality Packaging carefully packaged RGADJ-3012

+ Product Details Size - 6"w X 20"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 28" x 28" duct opening (measured at the opening)

+ Product Details Size – 26"w X 14"h is the size for the duct opening measurement only

+ Product Details Compact and Secure Design - Measures 3-7/8" wide x 3-1/2" high x 3" deep

8" x 12" or 12" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Aluminum White [Outer Dimensions: 10.5" X 14.5"] w12h12 + Product Details Size 7" Round Duct Pipe Quality Packaging carefully packaged RGADJ 3012 + Product Details Size 6"w X 20"h is the size for the duct opening measurement only + Product Details Perfect Fit & Easy Sizing Designed for a 28" x 28" duct opening (measured at the opening)