The Siemens 5SM3356-6 is a SENTRON residual current circuit breaker (RCCB), 4-pole, Type A, rated 63 A at 40 °C with a 500 V AC supply voltage. It's an instantaneous design — no intentional time delay — so it trips on the fault-current waveform as it occurs, which matters when coordinating with upstream overcurrent devices.
Snaps onto DIN rail (REG profile), occupies 4 width units at 36 mm wide. Depth is 70 mm, same as the installation depth — no extra clearance needed behind the rail. IP20 with conductors connected and the distribution board installed; that's enclosed-panel protection, not open-air.
At 50 °C it derates to 60.48 A, at 55 °C to 57.96 A, stepping down to 50.4 A at 70 °C. The permissible I²t is 70,000 A²s, and the let-through current rating is 7,500 A, which are the numbers the downstream cable and busbar sizing depend on.