It gives you three normally open (NO) auxiliary contacts, each rated for 10 A maximum, in a compact 36 mm wide package that clips onto the contactor without extra hardware. This isn't a standalone relay — it's a bolt-on contact block for the SIRIUS line. The spring-loaded terminals accept 2x (0.5... 1.5 mm²) with ferrules or 2x (0.5... 2.5 mm²) solid, which saves the panel wireman a screwdriver turn on every termination.
The headline 10 A maximum is the thermal current (Ith) — what the contacts can carry continuously in a resistive load. But the real-world switching limit depends on voltage and duty. At 24 V DC the contacts are rated for 6 A inductive; at 110 V DC that drops to 1 A. For AC control circuits you get 10 A at 230 V AC, and at AC-15 duty (solenoid valves, contactor coils) at 690 V the rating is 1 A. Mechanical life is 10 million cycles typical, which outlasts most contactors it'll ride on.
Snap-on mounting means zero tools for installation — push it onto the contactor front and it locks. The depth is 47.7 mm, which sits within the envelope of the base contactor; no extra DIN rail space is consumed.