18"w X 20"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 19.75"w x 21.75"h] Color_R-4.2 Yellow + Product Details Size –

+ Product Details Size – 24" x 24" with 6" collar T-Bar drop ceiling perforated return grill - metal back casing

+ Product Details Size - 30"w X 25"h is the size for the duct opening measurement only

Actual Filter Size – 21 3/4"w x 13 3/4" x 1"

The back is completely insulated

actual front end outer dimensions are approximately 18 5/8" width X 18 5/8" height

18"w X 20"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 19.75"w x 21.75"h] Color_R-4.2 Yellow + Product Details Size –+ Product Details Size 18"w X 20"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 19. 75" Width X 21. 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