40"W X 4"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 41.25"W x 5.25"H] Height_14in + Product Details 18"w X

+ Product Details 18"w X 18"h is the size for the drywall opening measurement only

Looks like it was just waxed

+ Product Details Perfect Fit & Easy Sizing - Designed for a 18" x 26" OR 26" x 18" duct opening (measured at the opening)

and two smaller loop pockets

40"W X 4"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 41.25"W x 5.25"H] Height_14in + Product Details 18"w X+ Product Details Size 40"W X 4"H is (for duct opening measurement only); actual front end outer dimensions are 41. 25" Width X 5. 25" Height. Design Designed for concealed, flush placement on your wall with a 3 8 inch space between louvers, this linear grille comes with an installation frame and clips for easy hook in assembly, ensuring a refined and seamless look. High Quality Aluminum The premium durable aluminum will never rust and it will never