The Siemens SIRIUS 3RT1924-5AD02 is a magnet coil for Size S0 contactors, designed for a 42 V AC control supply at 50 Hz. It uses spring-type terminals for the coil connection, which is the standard for the S0 frame in the SIRIUS family. This coil is the replacement part for contactors in that size range — if you have a 3RT1 contactor with a failed coil, this is the drop-in spare.
This coil mounts directly onto a SIRIUS Size S0 contactor base. No rewiring of the control circuit is needed if replacing a failed coil on an existing 3RT1 contactor; the 42 V AC 50 Hz rating is identical.