3 WAY Aluminum Supply Grille for 6x6 Duct Opening, White, Steel 1/2 inch spaced fins set at 40 degrees. Primary use: Side wall and ceiling. Screws are included with the system, standard. Durable white powder coated. Standard color is white (Ral9016). Aluminum construction, last long, rust proof 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 6 inches wide by 6 inches tall, order 6x6 option. For this particular product you're viewing at the moment, the hole on your wall/duct opening should be 6x6 duct opening. Click the 'Add To Cart' button now to order your Air Supply Grille!