20"w X 22"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 23.75"h] 18" Diameter and utility rooms

and utility rooms

actual front end outer dimensions are approximately 22" width X 16" height

16" Circular Round Aluminum HVAC Supply Grille Air Diffuser - With Butterfly Damper - Vent Duct Cover

+ Product Details Size – 16" x 18" or 18" x 16" is the size for the duct opening measurement only

+ Product Details Size - 30"w X 12"h is the size for the duct opening measurement only

20"w X 22"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 23.75"h] 18" Diameter and utility rooms+ Product Details Size 20"w X 22"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 75" Width X 23. 75" Height Weather and Pest Proof These louvers are especially designed to prevent water from entering your home, and with a built in back 1 2" mesh they also protect you from annoying rodents like mice, rats, birds, and squirrels High Quality Aluminum The premium durable aluminum will never rust and it will never