Square D EZ Meter-Pak meter centers provide reliable, versatile, and compact multi metering equipment for multi unit residential and commercial construction. The main devices are available as main circuit breakers, main fusible switches, or main lug terminal boxes. The compact footprint makes them easier to handle and install. Visi-Tite nuts eliminate the need for time-consuming torque readings when connecting devices. External mounting channels permit immediate installation with no disassembly or adjustment required. EZM main devices are suitable for use as service equipment with required grounding and bonding. This main circuit breaker provides 1 phase in, 1 phase out for a 3 wire configuration. It accepts 120/240VAC incoming service from OH or UG feeds. The unit is rated for 300A with the busbar rated for 400A. It has a short circuit current rating of 65kA. The enclosure is painted steel Type 3R. This EZ Meter-Pak meter center complies with UL standards.