The Siemens 5SU1356-0DV25 is a combined residual-current device and miniature circuit breaker (RCBO) — an FI/LS-protector in Siemens' 5SU series. It packs ground-fault and overcurrent protection into a single 1+N-pole unit, saving a DIN-rail slot over separate RCD + MCB. The Type AC designation means it detects sinusoidal AC residual currents only; for pulsed DC or mixed-frequency faults you would need Type A or F. The pig-tail connection (factory-fitted neutral tail) simplifies wiring in distribution boards that use a separate neutral busbar.
The 70 mm depth (D=70mm) fits standard enclosures; check clearance if the board has a shallow cover or door-mounted equipment. The pig-tail neutral is factory-terminated — no field crimp required, but verify the tail length reaches the neutral busbar before tightening. 1+N-pole configuration: the switched phase and neutral are both disconnected on fault, meeting isolation requirements for single-phase final circuits. The neutral pole is not overload-protected (the B-curve thermal-magnetic element is on the phase side only).