The Siemens 5SL6103-6CC is a 1-pole miniature circuit breaker rated for 3 A with a B-curve trip characteristic, breaking 6 kA at 230/400 V. It's a Basic Device from the current-production 5SL6 family — still active, still on the line.
Single-pole means it only switches the line conductor; neutral is continuous. That's fine for a 230 V phase-to-neutral circuit or a single phase of a three-phase system where you're protecting each leg individually.
Listed as Active — Siemens is still manufacturing this code. No phase-out or last-time-buy has been announced as of the latest lifecycle record. RoHS compliant since June 2013. The REACH declaration notes lead (CAS 7439-92-1) above the 0.1% threshold in the candidate list — standard for electrical contacts that use leaded solder or plating. No UL or CSA listing is stated in the available documentation, so verify local code acceptance if the panel requires a UL 489 mark.
Snaps onto standard DIN rail. Single-pole module takes one 18 mm width. The B-curve and 3 A rating suit it for lighting circuits, small control transformers, or general-purpose receptacle protection in a sub-distribution board.