28"w X 36"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 29.75"w x 37.75"h] 2-Way + Product Details Size – 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size – 14"w X 25"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 18" x 16" OR 16" X 18" duct opening (measured at the opening)

+ Product Details Size - 16"w X 36"h X 2"d (for duct opening measurement only)

+ Product Details Size - 16"w X 22"h X 2"d (for duct opening measurement only)

Actual Filter Size – 11 3/4"w x 19 3/4" x 1"

28"w X 36"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace Weather Resistant Air Grille with Screen Mesh [Outer Dimensions 29.75"w x 37.75"h] 2 Way + Product Details Size – 4 X 12 Is CRFG2028 Width_14in + Product Details Size – 14"w X 25"h is the size for the duct opening measurement only + Product Details Perfect Fit & Easy Sizing Designed for a 18" x 16" OR 16" X 18" duct opening (measured at the opening)