The MJB012103 Surface Mount J-Box, part of the most diverse surface mount offerings available, 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.