What it is and what it does
The Siemens SENTRON 5SY4104-6CC11 is a 1-pole miniature circuit breaker (MCB) with a B-curve tripping characteristic, rated 4 A at AC and a breaking capacity of 10 kA per EN 60898. That 10 kA rating means it can safely interrupt a fault current up to that level without welding its contacts or cascading the fault upstream — critical for selectivity in a distribution panel. The B-curve (3–5× In) is the standard choice for resistive and general-purpose loads; it will hold through a mild inrush but trip fast on a hard short.
Where it fits
This MCB snaps onto a DIN rail via the quick-assembly system, occupies a single modular width of 18 mm, and can be mounted in any position. The depth of 76 mm and installation depth of 70 mm mean it sits flush in a standard 18 mm wide slot with no extra clearance needed behind the rail. IP20 with connected conductors is normal for a panel-mounted breaker — it's protected against finger contact but expects to live inside an enclosure.