The Siemens 5SU1324-6FA25 is a 2-pole RCBO from the SENTRON series — a combined overcurrent and residual current device that fits a single modular-width slot in a DIN-rail distribution board.
The 25 A rating holds at 30 °C ambient, but drops to 23.5 A at 40 °C, 22.75 A at 45 °C, and continues down to 18.25 A at 70 °C. If the distribution board runs warm — say, tightly packed with other breakers — size the upstream protection against the derated figure, not the 30 °C number. The device is IP20 with conductors connected, so it's intended for enclosed panels only. Feed from top or bottom.