The MGP36450LV is a Schneider Electric PowerPact M unit mount circuit breaker with an electronic trip unit rated 450 A, 3-pole, 18 kA interrupting capacity at 600 VAC. It ships with control wire and lugs off the end for line and load terminations.
The 450 A electronic trip handles motor or feeder circuits at that continuous current. Unit mount form factor bolts into a switchboard or panel; lugs off the end accept cable terminations directly.