The Siemens 5SV4345-0 is a 4-pole residual current operated circuit breaker (RCCB), type AC, rated 125 A with 30 mA sensitivity on a 400 V AC supply. The 30 mA trip threshold covers personnel protection against direct-contact faults — the standard for general-purpose socket circuits and wet-area final subcircuits. The 125 A frame means it handles main-switch or submain duty in larger distribution boards, not just branch circuits.
RoHS compliant since 02-06-23. REACH candidate-list information is available on request. Note the national-installation-regulations caveat on the description: this device is not permitted in all countries, so verify local acceptance before specifying.