Galvanized steel enclosure. Single phase, 3 wire, insulated/bondable split neutral, 20 (1") spaces, 40 poles, 120/240 volt. Has notch for No.BRHDK125 hold down kit. Ground bar kits (necessary for sub-feeding) sold separately. 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. #1 - 300 kcmil wire range. Electrostatic powder coat, baked urethane painted. Rotate 180 degrees for bottom feed. 14-5/16" x 23" x 3-7/8". UL Listed file E52977.