The Siemens 5SL4603-6CC is a SENTRON miniature circuit breaker with a B tripping characteristic, rated 3 A at 400 V AC across 4 poles (3P+N). The 4-pole design with switched neutral (3P+N) suits three-phase final circuits where you need to isolate all live conductors, common in multi-story residential or small commercial panels.
It accepts conductors from 0.75 mm² up to 25 mm², which covers standard building wiring up to 6 mm² for the 3 A rating. Mounting position is unrestricted, so it can be installed horizontally or vertically without derating.