The Siemens 5SL3115-7 is a SENTRON 5SL miniature circuit breaker (MCB) rated 1.6 A at 400 V AC with a C tripping characteristic. One pole, 18 mm wide — that's one modular width on a DIN rail.
That's the standard choice for lighting, small resistive loads, and moderate inrush from control transformers. At 1.6 A this MCB protects a branch circuit feeding a handful of lighting fixtures or a small control transformer. The 4.5 kA SCCR matches typical domestic and light commercial service entrance ratings — adequate for most residential panels and sub-distribution boards. Tightening torque is 2.5 to 3 N·m.
At 18 mm wide (one modular unit,), it takes minimal rail space — useful when packing multiple circuits into a small enclosure. IP20 with connected conductors — keep it inside a dry enclosure.