The MGP36450SA is a Schneider Electric PowerPacT M unit mount circuit breaker with an electronic trip unit rated 450 A, 3-pole, interrupting 18 kA at 600 VAC. It includes a shunt trip for remote opening and ships with lugs off the end for line/load connections. This is a unit mount form factor — bolts directly into the switchboard or panel bus, not a DIN-rail or plug-in base.
The electronic trip unit provides adjustable long-time, short-time, instantaneous, and ground-fault protection curves, unlike a thermal-magnetic breaker. The shunt trip (factory-installed) allows a remote signal to open the breaker, common in emergency-stop or fire-safety circuits. Unit mount means the breaker frame bolts directly to a bus or mounting pan — verify the mounting hole pattern and bus spacing against your existing panel cutout.