The Siemens SIRIUS 3RH2911-2DE11 is a lateral auxiliary switch block designed to snap onto 3RT2 contactors. It provides one normally-open and one normally-closed contact pair on each side — left side carries 41/42 (NC) and 53/54 (NO), right side carries 23/24 (NO) and 31/32 (NC) — giving you four isolated signal paths from a 10 mm wide block. This is the solid-state-compatible variant, rated for 0.3 A at both 24 V and 60 V, with a contact reliability spec of one incorrect switching per 100 million operations at 5 V, 1 mA. That means it plays nice with PLC inputs and low-voltage DC loads without the gold-plating issues some standard auxiliary contacts have at dry-circuit levels.
Spring-loaded terminals accept 2x (0.5 to 1.5 mm²) with ferruled ends or 2x (0.5 to 2.5 mm²) solid/stranded. AWG equivalent is 2x (20 to 14). No screwdriver needed for wiring — strip to 8 mm, push in, done. That saves time on a panel with dozens of these blocks. Mechanical life is 5 million operating cycles typical. The block snaps onto a 35 mm DIN rail (DIN EN 60715) and measures 10 mm wide × 61.2 mm high × 66 mm deep — it adds negligible width to the contactor stack.