16"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Black [Outer Dimensions 17.75"w x 17.75"h] Compatible with Duct 10" + Product Details Size -

+ Product Details Size - 10"w X 26"h is the size for the duct opening measurement only

+ Product Details Size - 28"w X 26"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 18" x 28" OR 28" x 18" duct opening (measured at the opening)

Check Out This Asin For Matching T-Bar Drop-Ceiling Grille: B007CNEJZK

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

16"w X 16"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - Black [Outer Dimensions 17.75"w x 17.75"h] Compatible with Duct 10" + Product Details Size -+ Product Details Size 16"w X 16"h X 2"d (for duct opening measurement only); actual front end outer dimensions are 17. 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