The SENTRON 5SM3642-0MJ is a type AC residual current circuit breaker (RCCB) from the 5SM3 design series, rated 25 A with 300 mA sensitivity and a 10 kA breaking capacity at 400 V, 3+N-pole, 50 Hz. The 50 Hz operating frequency is fixed; not suitable for DC or variable-frequency circuits without additional filtering.
Mounts on standard DIN rail in the panel. The 4-module width (approx. 72 mm) fits a standard 4-pole RCCB slot. No neutral switching concern here: the 3+N-pole design switches all three phases and the neutral, so it drops into a 4-wire distribution board without extra wiring.