The Siemens 3RH1921-1EA02-Z is an auxiliary contact block with screw terminals, belonging to the 3RH1 series of contactor accessories. It mounts onto the front or side of SIRIUS 3RT contactors and 3RH contactor relays to add extra signal or control contacts without expanding the panel footprint.
The screw terminal version (Z suffix) accepts solid or stranded copper conductors up to 2.5 mm², with a strip length of 8–9 mm. It clips onto the contactor body without tools and occupies no additional DIN rail space — the contactor's own mounting carries it.