The Siemens 5SU1356-7KK13 is a SENTRON RCBO — a combined residual-current and overcurrent protection device in a single 2-module-wide (36 mm) package. It protects a 1P+N circuit (one protected pole plus switched neutral) with a C-curve thermal-magnetic trip and integrated residual-current sensing. Rated 13 A at 30 °C ambient, it's sized for final subcircuits feeding socket outlets or light commercial loads on a 230/240 V single-phase supply at 50 Hz.
The headline 13 A rating applies at 30 °C. The derating curve is published: 12.48 A at 40 °C, 12.22 A at 45 °C, 11.96 A at 50 °C, 11.57 A at 55 °C, 11.31 A at 60 °C, 10.53 A at 65 °C, and 10.01 A at 70 °C. If your panel ambient runs 50 °C, size the load to 11.96 A continuous — not the 13 A label. IP20 only once installed with conductors connected.
Two modular-width units (36 mm wide) snap onto a DIN rail. Depth is 77 mm, installation depth 70 mm — verify the gland plate clearance if the panel is tight. Supply can feed from either top or bottom; mounting position is unrestricted. The test button requires a minimum of 195 V to function.