Code-gauge steel enclosure. Single phase, 3 wire, solid neutral, 8 spaces and 16 circuits maximum 1-pole, 4 QP breakersmaximum 2-pole, 120/240 volt. 10,000 AIR. One piece plated aluminum bus bar. 100 percent circuit breaker twistouts. Positive load side circuit breaker hook rail. Suitable for use as service entrance equipment when a main breaker (125 amp maximum) is back-fed in branch position and used with main breaker retainer clip No.MBR1. When used as service equipment,any unused neutral position may be used for equipment grounding. Rotate entire device 180 degrees for bottom feed. Grayenamel finish. 12-3/8" x 14-3/4" x 3-7/8". UL Listed, complies fully with NEC and UL requirements for Class CTL.