6"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 7.75"w x 17.75"h] 8" Round Duct Pipe + Product Details Size –

+ Product Details Size – 24" x 24" with 8" collar T-Bar drop ceiling perforated return grill - metal back casing

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 36" OR 36" x 20" duct opening (measured at the opening)

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 28" OR 28" x 20" duct opening (measured at the opening)

Actual Filter Size – 11 3/4"w x 7 3/4" x 1"

6"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 7.75"w x 17.75"h] 8" Round Duct Pipe + Product Details Size –+ Product Details Size 6"w X 16"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 7. 75" Width X 17. 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