The 3RT5956-1CB00 is a SIRIUS surge suppressor, built as an RC element. It bolts onto the coil terminals of a contactor or relay to snub the inductive kick — that spike that eats contacts and radiates noise back into the 24 VDC control bus. Rated for AC/DC control supply voltage, it covers DC coils from 24 to 70 V and AC coils at 24 to 48 V at both 50 Hz and 60 Hz.
This is a snap-on accessory for the SIRIUS contactor range. No extra DIN rail space needed — it clips directly onto the contactor coil terminals.
Current-production part.