The FRU is a system component which needs to be fed from an Fiber Master Units (FMU). It is a band selective repeater optimized for radio communication systems operating in the frequency bands 2700 - 88 MHz and is designed for use specifically in Trunked Radio as well as mobile communication Systems.

To provide radio coverage in confined areas, the RF-input/ output of the repeater is connected to an antenna, radiating cable or both combined.