The Schneider Electric A9N21598 is a Clario iDPN N miniature circuit breaker rated 20 A, 3P+N, with a C-curve trip characteristic and a 6 kA breaking capacity at 400 V AC (EN/IEC 60898-1).
For a domestic or light commercial distribution board, that's the standard fault level; if your installation's prospective short-circuit current exceeds 6 kA, you'd step up to a higher-breaking MCB or add a backup fuse. The C-curve (magnetic trip at 5 to 10 x In) means it tolerates moderate inrush currents — typical for motor starters, small transformers, or fluorescent lighting banks — without nuisance tripping. The 20 A rating suits branch circuits feeding socket outlets or general-purpose loads up to roughly 4.6 kW on a 230 V single-phase leg. Clip-on DIN-rail mounting (9 mm pitches: 6) and tunnel-type terminals accepting up to 16 mm² rigid cable make it straightforward to integrate into a standard panel. The IP20 finger-safe terminals are fine for enclosed distribution boards; no washdown rating here.