The Schneider A9DC8606 is an Acti9 iCV40H residual-current circuit breaker with overcurrent protection (RCBO) — a single module that combines a 6 A C-curve MCB with a 300 mA earth-leakage trip in a 1P+N package.
The thermal-magnetic trip element handles overloads via a bimetal strip and short-circuits via a solenoid; the 300 mA earth-leakage sensitivity is set for personnel protection against indirect contact (not direct touch, which requires 30 mA). That 300 mA level is common for circuits feeding fixed equipment where the earth-fault loop impedance is known to be low enough to clear a fault within the disconnection time. The 20,000 electrical and mechanical cycles give a service life well beyond what a typical residential or commercial panel sees — you are not replacing this because it wore out.
Clip-on DIN rail mounting, 4 x 9 mm pitches wide (36 mm) for the 1P+N format. Neutral is on the left. Tunnel terminals accept 1 to 16 mm² rigid or 1 to 10 mm² flexible cable; strip 14 mm and torque to 2 N·m. The IP40 rating on the modular enclosure itself covers tool and wire access.