Harmony Relay. Plug-in base for narrow interface relays RSL with coil voltages of 60 VDC. 110 VAC/DC can be connected as control voltage, which is adjusted to the coil voltage of 60 V. The plug-in base contains an LED to display the control status, a lever for easy removal of the relay and a protection module. The cable connections are made via spring-loaded terminals. Comb-type busbars can also be connected.