20"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 9.75"h] 14" Round Duct Pipe also called T-Bar systems

also called T-Bar systems

+ Product Details Size - 36"w X 18"h is the size for the duct opening measurement only

Actual Filter Size – 35 3/4"w x 25 3/4" x 1"

Actual Filter Size – 29 3/4"w x 19 3/4" x 1"

20"w X 8"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 21.75"w x 9.75"h] 14" Round Duct Pipe also called T-Bar systems+ Product Details Size 20"w X 8"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 21. 75" Width X 9. 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 wear