The SMJB is a 10 cubic inch, surface mount J-box machined of solid brass. The SMJB represents the highest possible quality in materials and construction available anywhere. Use when surface mounting 12v or 120v fixtures where you need a wiring box to endure even the harshest elements; ideal for coastal applications. Our proprietary gasketed and screwless faceplate eliminates twisted wires and visible hardware, making fixture installations fast and neat. Standard 10 cubic inch size with 4 and 8 cubic inch screw on extensions making 10, 14 and 18 cu. boxes or use multiple extensions as needed. 1 or 2 hole faceplate and machined plugs included.