18"w X 22"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 19.75"w x 23.75"h] Aluminum Bar the gap will expand and 14" Round Duct Pipe FR M 414 White For 10 duct opening

the gap will expand and retract to meet perfect air supply needed

+ Product Details Size - 10"w X 20"h X 2"d (for duct opening measurement only)

+ Product Details Size - 22"w X 18"h X 2"d (for duct opening measurement only)

+ Product Details Perfect Fit & Easy Sizing - Designed for a 16" x 28" OR 28" X 16" duct opening (measured at the opening)

accordion dt { margin-bottom: 10px

18"w X 22"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace Weather Resistant Air Grille with Screen Mesh [Outer Dimensions 19.75"w x 23.75"h] Aluminum Bar the gap will expand and 14" Round Duct Pipe FR M 414 White For 10 duct opening the gap will expand and retract to meet perfect air supply needed + Product Details Size 10"w X 20"h X 2"d (for duct opening measurement only)