28"W X 4"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 29.25"W x 5.25"H] w25h25 High Quality – Commercial grade Compatible with Duct 4" RG1612AL actual front end outer

High Quality – Commercial grade aluminum - will never rust - designed for warehouses

+ Product Details Size & Compatibility – The size of galvanized sheet metal oval stack head with collar is 12" X 6" - 6" and it is compatible with Duct 6"

+ Product Details Size - 18"w X 28"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 26" x 8" OR 8" x 26" duct opening (measured at the opening)

Actual Filter Size – 23 3/4"w x 9 3/4" x 1"

28"W X 4"H [Duct Opening] Linear Aluminum Clip On Bar Return Air Grille [Outer Dimensions: 29.25"W x 5.25"H] w25h25 High Quality – Commercial grade Compatible with Duct 4" RG1612AL actual front end outer High Quality – Commercial grade aluminum will never rust designed for warehouses + Product Details Size & Compatibility – The size of galvanized sheet metal oval stack head with collar is 12" X 6" 6" and it is compatible with Duct 6"