The Type A 300 mA residual-current element detects pulsating DC fault currents as well as AC, so it covers single-phase rectifier loads like switched-mode power supplies and LED drivers, not just pure sine-wave faults.
Where you'll find it in a panel
Snaps onto DIN rail in a distribution board or sub-panel. Four modules wide (about 72 mm), so it eats a little more rail space than a standard MCB — plan the fill factor when laying out a multi-circuit board. The 2-pole version switches both line and neutral, which is the usual arrangement for single-phase final circuits in European-style TN or TT systems.