From the Manufacturer The Steel City 5215112 is a pre-galvanized steel square box with 12Inch conduit knockouts. Is a 4Inch box that is 112Inch deep with an 18Cubic Inch capacity and is intended for use conduits. On each side of the box there are three 12Inch conduit knockouts while the bottom has five conduit knockouts and both sides have three. The knockouts provide better contact with the conduit fitting and locknut to the box while improving the grounding path. The box protects the device from damage and gives access to the wiring even after the construction is complete. Steel City is the industries leading product line of metallic switch and outlet boxes used in electrical construction. Since 1904, its products have represented the highest quality standards in manufacturing and innovative design, with one of the most complete offerings available