Extension Ring, Box Type Square, Number of Gangs 2, Bracket Type -, Capacity 22.5 cu in, Material Galvanized Zinc, Number of 1/2 In. Back Knockouts 0, Number of 1/2 In. Side Knockouts 12, Nominal Depth 1 1/2 in, Nominal Length 4 in, Nominal Width 4 in, Color Silver