6"W X 6"H [Duct Opening] Never Rust Plastic 4-Way-Vertical Air Supply Register - HVAC Vent Duct Grille - Off White [Outer Dimensions: 7.75"W X 7.75"H] Color_R-4.2 Yellow + Product Details Size - 4 X 12 Is CRFG2028 Width_14in

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

+ Product Details Size - 26"w X 36"h is the size for the duct opening measurement only

and squirrels

Actual Filter Size – 25 3/4"w x 7 3/4" x 1"

+ Product Details Size - 30"w X 10"h is the size for the duct opening measurement only

6"W X 6"H [Duct Opening] Never Rust Plastic 4 Way Vertical Air Supply Register HVAC Vent Duct Grille Off White [Outer Dimensions: 7.75"W X 7.75"H] Color_R 4.2 Yellow + Product Details Size 4 X 12 Is CRFG2028 Width_14in + Product Details Size 20"w X 6"h is the size for the duct opening measurement only + Product Details Size 26"w X 36"h is the size for the duct opening measurement only