The Siemens SENTRON 5SL4225-8 is a 2-pole miniature circuit breaker with D tripping characteristic, rated 25 A at 400 V AC and a 10 kA breaking capacity per EN 60898.
At 30 °C ambient the breaker holds its full 25 A rating, but at 40 °C it derates to 23.1 A, and at 55 °C to 19.91 A. If your panel runs warm — typical for a packed enclosure — you need to factor that derating into the branch circuit design, not just the label current. Two modular-width units (36 mm) snap onto standard DIN rail.
Lifecycle status is current — no end-of-life notice on record. The 5SL4225-8 is still an active catalogue number in the SENTRON family, so it is not a last-time-buy or obsolete line.