The Schneider Electric A9K23125 is an Acti9 iK60N miniature circuit breaker (MCB) rated at 25 A, single-pole, with a B tripping curve and a 6000 A breaking capacity at 230 V AC. It uses a thermal-magnetic trip unit and clips onto a DIN rail for panel mounting.
In a warm panel (ambient above 30 °C), derate per the manufacturer's curve — a 25 A breaker in a 40 °C enclosure may need to be loaded to no more than 22 A. The B curve trips magnetically at 3–5× In (75–125 A), fast enough to clear a hard short before downstream wiring heats, but not so sensitive that it nuisance-trips on the inrush of a few fluorescent fittings or a small control transformer. The single-pole (1P) version protects one phase leg. For a 230 V AC single-phase circuit, that is the line conductor; the neutral is switched by a separate device or busbar. The toggle gives ON/OFF indication, and a padlocking device can lock it in the OFF position for lockout/tagout.
Height is 85 mm, depth 78.5 mm.