The Siemens SIRIUS 3RH1921-2HA13 is a 4-pole auxiliary switch block with 1 normally open and 3 normally closed contacts, designed to snap onto 3RT1 contactors and contactor relays. It uses spring-loaded terminals for the auxiliary and control circuit wiring, accepting 2x (0.5 to 2.5 mm²) without core end processing or 2x (0.5 to 1.5 mm²) with ferrules. The block is rated for a maximum of 10 A, with specific contact ratings depending on voltage: 6 A at 24 V, 6 A at 125 V, 6 A at 230 V, 6 A at 250 V, 3 A at 400 V, and 0.3 A at 220 V.
The AC-15 rating at 690 V is 1 A, which governs switching of solenoid and contactor coils at that voltage. The surge voltage resistance is 6 kV, and the insulation voltage at pollution degree 3 is 690 V AC. The block carries IP20 protection on the front, so it's for use inside an enclosure, not exposed to washdown.