This 4-inch octagonal box is designed for built-in mounting in walls and ceilings. It features cable straps for NM cable and a depth of 2-1/8 inches, offering a cubic capacity of 21 cubic inches. Made from durable steel, this silver box provides a reliable enclosure for electrical connections.The PROSERIES 54171-L is a 4-inch octagonal electrical box with a depth of 2-1/8 inches and a cubic capacity of 21 cubic inches. It is constructed from steel and features cable straps for NM cable. The box is designed for wall or ceiling mounting and has a width of 101.6 mm. It is rated as weatherproof 'N'.