The Siemens 5SL5108-7RC is a 1-pole miniature circuit breaker (MCB) rated for 220 V DC with a 10 kA breaking capacity and a C-curve trip characteristic at 8 A. It's a DC-rated MCB, which means it's built to handle the arc extinction demands of direct-current circuits — a different animal from an AC MCB, since a DC arc doesn't have a natural zero-crossing to self-extinguish.
The 1-pole form factor means it protects a single DC line — common in DC auxiliary circuits, control power supplies, or battery-backed loads in industrial panels.