12"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 13.75"w x 19.75"h] Grille this model allows for mounting 4 X 12 Is CRFG2028 Width_14in

this model allows for mounting without removing the thermostat

Actual Filter Size – 27 3/4"w x 7 3/4" x 1"

+ Product Details Size – 12" x 24" or 24" x 12" is the size for the duct opening measurement only

+ Product Details Size – 36"w X 12"h is the size for the duct opening measurement only

making it a versatile choice for both residential and commercial settings

12"w X 18"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace Weather Resistant Air Grille with Screen Mesh [Outer Dimensions 13.75"w x 19.75"h] Grille this model allows for mounting 4 X 12 Is CRFG2028 Width_14in this model allows for mounting without removing the thermostat Actual Filter Size – 27 3 4"w x 7 3 4" x 1"