Advantage FeaturesEXMAX EXD-6824 Wireless tour guide system enable up to two tour guides speech on the same channel in each group, allowing them to take turns at regular intervals to reduce fatigue. Transmitter also has an AUX input which enables to connect a MP3, Smartphone, MP4 to the system, to play background music or pre-recorded voice files. 9999 Selectable 2.4GH z licence-free global channels accommodate hundreds of groups working simultaneously as long as they work on the different channels.