The Siemens SIRIUS 3RH1440-1BG40 is a Size S00 auxiliary contactor — four instantaneous normally-open contacts rated 10 A at 24 V, stepping down to 1 A at 690 V. It's the signal-switching side of a motor starter or a standalone logic element for control circuits, not a power contactor. The 6 kV rated surge voltage and pollution degree 3 tell you it's built for industrial panels where transients and dust are normal. Coil holds at 3.2 W DC closing and holding power, so the control transformer budget is predictable.
Screw and snap-on mounting onto DIN rail — the Size S00 footprint (57.5 mm high, 90 mm wide, 72 mm deep) fits the standard panel grid. That matters when you're squeezing this into a crowded enclosure behind a gland plate. Solid wire terminations accept 2x 0.5–1.5 mm², 2x 0.75–2.5 mm², or 2x 4 mm² — spring-cage or screw terminals depending on the variant, but the cross-section range covers control wiring from signal loops to short power feeds.
Shock resistance is 10g for 5 ms and 5g for 10 ms — enough for machine-mounted applications but not for direct engine-block mounting without isolation. The typical mechanical life of the contactor block is 5 million operations.