The Schneider Electric DOM12252SNI is a Domae-series miniature circuit breaker — 1 pole, 4 A rated current, C-curve trip characteristic, with a 4.5 kA breaking capacity at 230 V AC per IEC 60898-1. It clips onto DIN rail, takes up two 9 mm pitches, and is intended for distribution boards protecting lighting or general-purpose AC circuits.
The single-pole form factor protects one phase; neutral is switched separately if needed. Comb busbar compatible, so it gangs neatly with adjacent breakers on the same DIN rail.