The Siemens SENTRON 5SL6604-7BB is a 4-pole (3P+N) miniature circuit breaker rated 4 A with a C-trip curve, breaking 6 kA per EN 60898 and IEC 60947-2 at 400 V AC. The 4 A rating limits continuous load to 4 A per phase, so it protects a 4 A final circuit — lighting strings, small fan coils, or control transformers — not a motor or heater bank drawing higher current.
The 5SL6604-7BB occupies 4 width units (72 mm) on a DIN rail, with a depth of 76 mm and an installation depth of 70 mm. It mounts in any position, which simplifies layout in crowded enclosures. The neutral pole is switched (3P+N), so it disconnects the neutral as well as the three phases, which is required in some national wiring rules (Italy version per the description).