The relay module RM2A contains two, the RM4A four relays. The relays are placed in a plastic housing for a  space-saving assembly on symmetrical top-hat rails (EN 50022).
Light-emitting diodes (LED) on the front side of the housing show the present state of the relays. The relay coils are independent of each other so that different potentials can be used (e.g. from different level crossing protection units) in a single module. The modules contain relays with a different number of forcibly and restricted forcibly guided contacts.  All contacts and coil connections are executed on plug-in clamps.