Expander E4 EX is an expansion module of the DUPLEX EX 2.4 GHz telemetry system. Up to 4 telemetry sensors can be connected to one DUPLEX receiver. Thanks to the Expander, data from multiple telemetry sensors can be monitored simultaneously, including set alarms. The JETIBOX terminal with the possibility of wireless information transmission by the DUPLEX EX 2.4GHz system is used to display the measured values.
English manual here.
German manual here.