The Siemens 5SU1656-1KV13 is a combined residual-current and miniature circuit breaker (RCBO) — an FI/LS protector. It has a Type AC residual-current device rated at 300 mA trip sensitivity with a 1+N-pole MCB, C-curve, 13 A, in a 70 mm-wide DIN-rail housing. The 6 kA breaking capacity suits it for final-subcircuit protection where the prospective short-circuit current stays under that threshold.
The 70 mm width occupies more panel real estate than a single-pole MCB — plan the enclosure fill accordingly. The Type AC designation means it detects sinusoidal AC residual currents only; pulsating DC faults will not trip it.