The Siemens 5SU9356-1KK63 is a SENTRON RCBO — a residual-current-operated circuit breaker that combines overcurrent and earth-fault protection in a single 2-module-wide (36 mm) package. It's a 1P+N design, meaning it switches and protects the line conductor only, with the neutral switched but not protected. The C-curve tripping characteristic means it holds up to 5–10× rated current for short-duration inrush (typical for motor-starting or transformer loads) before tripping magnetically. Rated 63 A at 30 °C ambient, it derates to 59.22 A at 40 °C, 57.33 A at 45 °C, 54.81 A at 50 °C, and 51.03 A at 55 °C. That derating curve matters when you're packing this into a warm enclosure — the 40 °C figure is the one to design to for a standard panel. The higher 10 kA figure gives you headroom for industrial distribution boards with higher prospective fault currents.
Installation depth is 70 mm. Mounting position is any orientation. Supply can come from either top or bottom — no mandatory orientation for the line feed.