The Siemens 3RH2911-2XA04-0MA0 is a SIRIUS auxiliary switch block that bolts onto the front of 3RT2 contactors and 3RH2 contactor relays. It gives you four normally-closed (NC) contacts — labelled 51/52, 61/62, 71/72, 81/82 — each rated for 10 A at 24 V and 6 A at 230 V, with spring-loaded terminals that accept 2x (0.5 to 2.5 mm²) solid or ferruled stranded wire. Snap it onto the DIN rail alongside the contactor — it takes up 36 mm width and 47.7 mm depth, so it fits a standard panel without hogging space.
The 10 A maximum at 24 V is the thermal current (Ith) — it'll carry that continuously in a resistive circuit. That means it's fine for 480 V line-to-line control circuits in industrial environments where dust and humidity are present — no derating needed for the typical panel.