20"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 13.75"h] 12" Round Duct Pipe Actual Filter Size – 17

Actual Filter Size – 17 3/4"w x 21 3/4" x 1"

+ Product Details Size - 14"w X 12"h X 2"d (for duct opening measurement only)

Actual Filter Size – 21 3/4"w x 23 3/4" x 1"

+ Product Details Size - 4"w X 18"h is the size for the duct opening measurement only

this guard ensures long-lasting protection and security

20"w X 12"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 13.75"h] 12" Round Duct Pipe Actual Filter Size – 17+ Product Details Size 20"w X 12"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 75" Width X 13. 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