It carries a 40 A rated current (In) and a 6000 A Icn breaking capacity at 220...240 V AC, 50 Hz, compliant with EN/IEC 61009-2-1. The integrated earth-leakage protection trips at 300 mA, so it covers ground-fault protection for final circuits where a 30 mA sensitivity would cause nuisance trips on longer cable runs or equipment with natural leakage.
Clip-on mounting to DIN rail, 36 mm width — four 9 mm pitches. IP20 on the device body, IP40 inside a modular enclosure — fine for distribution boards and residential/commercial consumer units.
Curve B means magnetic trip between 3 and 5 times In — 120 to 200 A instantaneously. That suits resistive loads and short cable runs where inrush is low; for motor or transformer circuits with higher starting surges, a Curve C or D would be the better call. The 300 mA residual sensitivity is sized for distribution sub-mains or socket-outlet circuits where 30 mA RCDs would nuisance-trip from cable capacitance or equipment leakage.