2.4GHz Wireless Digital transmission of audio signal excludes external interference and promises clear voice 
Anti-oxidation, durable aluminum outdoor unit 
Name or room number of the user can be displayed on the outdoor unit, along with LED indication 
It's battery-operated when power failure occurs; and it transfers to AC power supplied when power comes 
Working distance near 500m in open area 
Easy DIY installation 
Outdoor unit surface mounted installation 
Accessories: one adapter and one protection cover for outdoor unit