The Siemens 5SU1324-6KX25 is a SENTRON RCBO — a combined residual-current circuit breaker and miniature circuit breaker in one 3-module-wide unit (54 mm wide, 77 mm deep, 90 mm high). It protects a final circuit against both overload/short-circuit and earth leakage, saving a DIN-rail position versus separate devices. Insulation voltage is rated 264 V.
At 40 °C it's 23.5 A; at 50 °C it's 21.75 A; at 60 °C it's 20.25 A; at 70 °C it's 18.25 A. If the distribution board runs warm — and most do, especially with high-density RCBOs — size the load to the derated figure, not the nameplate 25 A.
Snaps onto standard DIN rail, any mounting position. Supply can enter from top or bottom. Installation depth is 70 mm plus the device depth of 77 mm — check the enclosure depth before panel layout. IP20 when installed in a distribution board with conductors connected; not for wet locations without an outer enclosure.