It's the part you add when the main contactor's built-in auxiliary contacts are already used up, or when you need a normally-open / normally-closed combination the base unit doesn't offer. Rated for a maximum switching current of 3 A, it handles 1 A at 24 V DC, 0.2 A at 125 V DC, and 0.1 A at 250 V DC — these are the numbers that govern whether it reliably breaks a PLC input or a small relay coil without welding contacts. The adjustable time-delay range of 0.5 to 10 s (with a 150 ms recovery time and a 200 ms minimum ON period) means this variant includes an onboard timer for sequenced start or delayed dropout — not every auxiliary switch in the SIRIUS family carries that.
Clip-on fastening means it snaps directly onto the front or side of a SIRIUS contactor without tools — no DIN-rail footprint consumed beyond the base unit itself. Wire termination accepts solid or stranded conductors from 18 to 14 AWG (2x 20...14 AWG solid), so it fits standard control wiring without pigtails or ferrule adapters.