The Schneider Electric A9KF71210BQ is an Acti9 K60 miniature circuit-breaker rated 10 A with a C curve, 2 poles, and a 10 kA Icn breaking capacity at 415 V AC conforming to EN/IEC 60898-1. The C curve (magnetic trip 5–10 × In) means it handles moderate inrush — typical for general-purpose distribution, lighting, and small motor loads — without nuisance tripping. The thermal-magnetic trip unit gives you both overload protection (bimetal strip) and short-circuit protection (solenoid) in one 36 mm wide, 2-pole package that snaps onto a DIN rail. Rated altitude 0–2000 m and pollution degree 2 cover the vast majority of indoor panel installations. The IP20 finger-safe terminals are fine inside a closed enclosure; if you're mounting this in a standalone box exposed to dust or moisture, the enclosure itself needs the IP rating.
The 36 mm width occupies 4 modules of 9 mm pitch — account for that in your rail fill calculation. Terminals accept 1–25 mm² rigid or 1–16 mm² flexible copper; strip length 14 mm, tighten to 2 N·m. The toggle actuator gives clear visual indication of tripped vs on/off state. No earth-leakage protection built in — if you need that, add a separate RCD downstream.