Electrical Box, Box Type Square with Bracket, Number of Gangs 2, Bracket Type H, Capacity 21 cu in, Material Steel, Number of 1/2 In. Back Knockouts 4, Number of 1/2 In. Side Knockouts 12, Clamp Type -, Number of 3/4 In. Back Knockouts 2, Number of 3/4 In. Side Knockouts 8, Nominal Depth 1 1/2 in, Nominal Length 1 1/2 in, Nominal Width 4 in, Color Gray, Standards UL Listed.