Return Air Grille for 30"x8" Duct Opening, Black, Steel 1/2"spaced fins set at 40 degrees. Primary use: Side wall and ceiling. Screws are included with the system, standard. All-steel construction. Durable black powder coated. Standard color is black. How To Measure A Grille Always measure the size of the duct opening (the "hole" in the duct/wall). Do not measure the entire size of the register itself. Size of the grille is; listed size +1.75-inch. Understanding Width & Height In a grille size, the first number always represents the width and the second one is the height. As an Example: If the hole on your wall/duct is 30" wide by 8" tall, order 30x8 option. If the hole is 8" wide by 30" tall, order 8x30 option. For this particular product you're viewing at the moment, the hole on your wall/duct opening should be 30"Wx8"H. Click the 'Add To Cart' button now to order your Return Air Filter Grille!