18"w X 24"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 19.75"w x 25.75"h] Aluminum only measure the "hole" in

only measure the "hole" in the wall/duct

Its professional design and solid construction make it the perfect solution for safeguarding your thermostat against unwanted access

These Supply Diffusers with integral round necks are recommended for heating

actual front end outer dimensions are approximately 21 5/8" width X 31 5/8" height

Designed for a 1" thick filter

18"w X 24"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - White [Outer Dimensions 19.75"w x 25.75"h] Aluminum only measure the "hole" in+ Product Details Size 18"w X 24"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 19. 75" Width X 25. 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