The Siemens 5SY4350-8CV is a 3-pole miniature circuit breaker rated 50 A with a D tripping curve and a breaking capacity of 15 kA at 400 V AC.
DIN-rail integration note
The 3-pole body takes three module-widths (about 54 mm) on the rail. For a panel OEM or MRO planner, that footprint is the same as any other Siemens 5SY series 3-pole — no surprises when swapping into an existing distribution board.