The Siemens 3RT1016-2AV01-ZW95 is a 3-pole contactor in the SIRIUS series, size S00, rated for AC-3 duty at 4 kW / 400 V. The AC 400 V 50/60 Hz coil pulls in on a standard line voltage, making it a direct fit for panels fed from a 400 V three-phase supply without a separate control transformer.
Size S00 snaps onto a 35 mm DIN rail and occupies roughly 45 mm of width — a compact footprint that leaves room for an overload relay or auxiliary contact block on the same rail. The AC coil draws its holding current from the 400 V line, so no 24 VDC power supply is needed for this contactor; just verify the coil voltage matches your control circuit before wiring.