It is a 2-pole unit wired as 1P+N — meaning it switches the line and protects the neutral but does not break the neutral on overload. The C-curve (rated for 5–10× In instantaneous trip) suits it for protecting general-purpose circuits with moderate inrush, like control transformers, contactor coils, or small lighting loads in industrial control panels. The higher IEC figure matters when the MCB is used as a branch-circuit protective device in an industrial panel with high available fault current — it can clear a 50 kA fault without rupturing. The quick-assembly fastening method means it snaps onto the DIN rail without tools.
Temperature derating — the real current rating on your BOM line
The 0.3 A rating is at 35 °C. At 40 °C it derates to 0.28 A; at 50 °C to 0.26 A; at 60 °C to 0.24 A.
Supply voltage frequency is 50/60 Hz, so it works on both mains standards without derating.