The Schneider Electric A9N21543 is an iDPN miniature circuit-breaker from the Clario range, rated 2 A with a C curve and 1P+N configuration.
The breaking capacity of 4500 A at 230 V AC is the maximum fault current it can safely interrupt — that's the standard residential/commercial level per EN/IEC 60898-1, fine for most distribution boards downstream of a higher-rated upstream breaker. The thermal-magnetic trip unit gives you the dual response: a bimetal for overloads and a solenoid for shorts.
Where it goes in the panel
Clip-on DIN rail mount, 18 mm wide — that's one modular pitch, so it takes up a single slot in a consumer unit or distribution board. The neutral is on the left, which matters for busbar alignment if you're populating a row of iDPN breakers. Tunnel terminals accept up to 16 mm² rigid or 10 mm² flexible, with a 2 N·m tightening torque and 13 mm strip length.