It combines a D-characteristic MCB for high-inrush loads (motors, transformers, welding equipment) with a Type A residual current device sensitive to pulsating DC fault currents up to 100 mA.
The 40 A continuous rating and D characteristic suit circuits where the load draws a high inrush — typically motor feeders, power supplies with large capacitive input filters, or industrial lighting banks. It is not suitable for pure DC fault currents (Type B required for that). The 4-pole construction (3 phases + neutral) makes it a drop-in for three-phase distribution boards where neutral protection and disconnection are mandatory per local wiring rules.