The Siemens SIRIUS 3RT1326-1AF00 is a 4-pole power contactor in the S0 frame size, rated for motor switching at 11 kW under AC-2 duty at 400 V. It carries 4 normally-open main contacts and zero NC main contacts, so it's a straight make/break device for a 3-phase motor plus one pole for an additional load or control circuit. The auxiliary contact block is separate and not included.
The S0 footprint — 61 mm wide, 85 mm tall, 91 mm deep — fits standard panel layouts; side-by-side mounting is permitted without derating for the AC-2 load given the listed clearance of 6 mm at the side. Screw terminals on the main circuit accept 2x (1 to 2.5 mm²) solid or 2x (2.5 to 6 mm²) stranded, with a maximum of 2x 10 mm². For AWG, that's 2x (18 to 14) or 1x 12. The auxiliary terminal block handles 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) — fine for control wiring.
Environmental and coordination
That's the selectivity figure a panel designer needs for the branch circuit.