12"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 13.75"w x 13.75"h] Round Damper Ring + Product Details Size - Compatible With Duct 7in Applications This sheet metal DDAG-A-1212

+ Product Details Size - 16"w X 18"h is the size for the duct opening measurement only

Actual Front End Outer Dimensions Are 8" Diameter

actual front end outer dimensions are approximately 32 5/8" width X 20 5/8" height

order a 14x20 grille

+ Product Details Size – 8"w X 18"h is the size for the duct opening measurement only

12"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace Weather Resistant Air Grille with Screen Mesh White [Outer Dimensions 13.75"w x 13.75"h] Round Damper Ring + Product Details Size Compatible With Duct 7in Applications This sheet metal DDAG A 1212 + Product Details Size 16"w X 18"h is the size for the duct opening measurement only Actual Front End Outer Dimensions Are 8" Diameter