The Type AC designation means it detects sinusoidal AC residual currents only; if your load includes rectifiers, VFDs, or switched-mode supplies that generate pulsed DC fault currents, you need a Type A or Type F device instead.
The 70 mm width (D=70mm) occupies four standard 17.5 mm DIN-rail module spaces — factor that into your enclosure fill when replacing a separate RCD and MCB combo that might take less total width. The 1+N-pole format switches the line conductor and disconnects the neutral, but the neutral pole is not switched on the overcurrent side; it opens only on residual fault.