26"w X 20"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace - Weather-Resistant Air Grille with Screen Mesh - [Outer Dimensions 27.75"w x 21.75"h] with filter + Product Details Size – Drop Ceilings / Aluminum The set includes a FG1836 HP-1

+ Product Details Size – 18" x 22" or 22" x 18" is the size for the duct opening measurement only

Actual Filter Size – 19 3/4"w x 21 3/4" x 1"

+ Product Details Size – 26"w X 22"h is the size for the duct opening measurement only

Actual Filter Size – 31 3/4"w x 29 3/4" x 1"

+ Product Details Size - 30"w X 2"h is the size for the duct opening measurement only

26"w X 20"h Aluminum Exterior Gable Louver Vent for Walls & Crawlspace Weather Resistant Air Grille with Screen Mesh [Outer Dimensions 27.75"w x 21.75"h] with filter + Product Details Size – Drop Ceilings Aluminum The set includes a FG1836 HP 1 + Product Details Size – 18" x 22" or 22" x 18" is the size for the duct opening measurement only Actual Filter Size – 19 3 4"w x 21 3 4" x 1"