Electrical Box, Box Type Square, Number of Gangs 2, Bracket Type Not Applicable, Capacity 21 cu in, Material Steel, Number of 1/2 In. Back Knockouts 4, Number of 1/2 In. Side Knockouts 8, Clamp Type -, Number of 3/4 In. Back Knockouts 2, Number of 3/4 In. Side Knockouts 4, Nominal Depth 1 1/2 in, Nominal Length 4 in, Nominal Width 4 in, Color Gray, Standards UL Listed For use with lighting fixtures, switches, or receptacles, this box can be installed in a ceiling or wall. Square boxes are used where multiple conductor runs are split into two or more directions to bring power to a number of electrical devices.