Galvanized steel enclosure. Single phase, 3 wire, insulated/bondable split neutral, 20 (1 in ) spaces, 20 poles, 120/240 volt. Main breaker type BR at 10,000 AIR. Tin-plated aluminum bus bar. Twin neutral with non-removable cross bus connecting them. When bonded, unused neutral connections may be used for equipment ground protectors in service entrance application. #4 - 1/0 wire range. Electrostatic powder coat, baked urethane painted. Rotate 180° for bottom feed; orientation of main breaker handle consistent with NEC 240-81 requirements because it operates horizontally. 14-5/16 in x 23 in x 3-7/8 in UL Listed file E52977.