The Siemens 3RH2122-2BE40 is a SIRIUS auxiliary contactor in frame size S00, carrying 2 normally open instantaneous contacts. This is a current-production part, so it's available through standard Siemens distribution channels — no last-time-buy or surplus hunt needed.
The 2 NO contacts are rated for AC-15 switching duty at several voltage levels: 10 A at 24 V and 230 V, 3 A at 110 V and 400 V, 2 A at 500 V, and 1 A at 690 V. For DC switching, it handles 10 A at 24 V, 4.7 A at 60 V, 1.2 A at 220 V, and 0.5 A at 440 V. These are the values that govern whether the contactor can handle your specific control-circuit load — a PLC output driving a 24 VDC relay coil is well within the 10 A rating, but a 440 VDC solenoid valve would need the 0.5 A limit checked against inrush.
Dimensions are 45 mm wide, 70 mm high, and 73 mm deep. The auxiliary switch extension capability (Product Extension Auxiliary Switch: Yes) means you can clip on additional contact blocks if the 2 NO count isn't enough for your feedback or interlock scheme.