Siemens 3RH2911-2HA12 auxiliary switch, on the front, 1 NO + 2 NC, .1/.2, .1/.2, .3/.4, --/--, current path: 1 NC, 1. Siemens 3RH2911-2HA12 is the exact printed commercial reference for a contactor relay / accessory accessory in the SIRIUS 3RH Contactor Relays range. Siemens' official product description is: auxiliary switch, on the front, 1 NO + 2 NC, .1/.2, .1/.2, .3/.4, --/--, current path: 1 NC, 1 NC, 1 NO, --, spring-loaded terminal, for contactors 3RT2 and contactor relays 3RH2.