The Schneider Electric A9KF71304BQ is a 4 A, 3-pole miniature circuit breaker from the Acti9 K60 range, built to EN/IEC 60898-1. It's a thermal-magnetic MCB with a C-curve (5–10 x In magnetic trip), rated to break 10 kA at 415 V AC. This is the part you spec for a 4 A lighting or general-purpose distribution circuit on a 3-phase panel — not a motor-protective device, but a standard branch-circuit overcurrent guard. The C-curve means it holds through inrush up to 5–10 times rated current before the magnetic trip fires, so it's a fit for mixed resistive and light inductive loads (contactors, small transformers, control transformers).
Rated for isolation per EN/IEC 60898-1, so it doubles as a disconnecting means for downstream work. That's a practical check for panel builders: you don't need a separate isolator ahead of this breaker if the circuit design allows.
Snaps onto a standard DIN rail (35 mm), fixed mounting. 54 mm wide — that's 6 modules of 9 mm pitch, which is the standard 3-pole width for this class. Height 81 mm, depth 70 mm. Tightening torque 2 N.m top or bottom. Wire strip length 14 mm. Keep it inside the enclosure. Pollution degree 2 (normal, non-conductive dust only). Operating altitude up to 2000 m, 95% RH at 55 °C, tropicalisation class 2 per IEC 60068-1. All standard for a distribution-grade MCB in a climate-controlled panel room.
Rated 20,000 electrical and 20,000 mechanical cycles. That's the endurance figure for the breaker's life under load — for a distribution board seeing occasional switching, it's more than adequate. The set ships as 4 units per package.