The Siemens 3RT1326-1AP00 is a SIRIUS-brand power contactor in size S0, with four normally-open main contacts rated for AC-2 duty at 11 kW on a 400 V line. That AC-2 rating covers slip-ring motor starting — the contactor handles the higher inrush and longer arcing of wound-rotor motors, not just standard squirrel-cage loads. The 50 Hz coil pulls in at 0.8 to 1.1 times rated voltage, so it holds in on a weak supply but drops out cleanly below that band. Side-by-side mounting is allowed — no derating gap needed when you pack them on the rail.
Dimensions are 61 mm wide, 85 mm tall, 91 mm deep — that's the S0 footprint, so it drops into the same cutout as other S0 contactors in the SIRIUS family without re-drilling the subplate. No NC main contacts are present, so it's not a reversing or star-delta configuration out of the box.
That gives the panel builder flexibility: if downstream protection is coordinated for selectivity, you can use the 35 A fuse and keep the contactor in service after a fault.