No electrical system can do without circuit breakers, as they are the stop signs acting when too much current is flowing through electrical wiring. They are essential devices and one of the most important safety mechanisms for the prevention of dangerous situations.
Too much charge flowing through a circuit at a certain moment will heat the wires of a appliance, causing unsafe situations and possibly fire. The task of a circuit breaker is quite easily explained: it will cut off/break the electrical circuit whenever the current rises above a safe level. Hence the name circuit breaker. Without circuit breakers (or the alternative: fuses), an electrical system is difficult to maintain because of the potential for fires and other problems.
This 70A circuit breaker (single pole) is of the CD1 range, designed for both AC and DC circuits and suitable for MasterVision electrical switchboards (Mastervolt's modular central switchboard with various monitoring functions).