The Siemens 5SY4350-6CC11 is a 3-pole SENTRON miniature circuit breaker rated 50 A with a B tripping characteristic and 10 kA breaking capacity at 400 V AC per EN 60898. This is the part you grab when the line-down call is a 50 A three-phase lighting or resistive load panel that needs fast overcurrent protection — the B curve trips at 3-5× rated current, so it clears short circuits fast enough to protect sensitive loads without nuisance tripping on mild inrush.
The 54 mm width (3 width units) and 70 mm installation depth leave room alongside other SENTRON modules on the same rail; the 76 mm overall depth fits standard 80 mm deep enclosures.