The EXMAX wireless audio transmission system could transmit voice of who speak to the microphone of transmitter to the ones who wear earphone of receivers,transmission distance is about 20-30 meters (65-100ft).40 frequency channels mean it has 40 select IDs allow at least 10 groups to work simultaneously.Widely used for field trip,tour exhibit guides,sermon interpretation,work-study,conferences,translation,audio visual laboratory,events for church,family,restaurants,hajj.Transmitter weighs 56g and receiver weighs 46g,Small and light for carry or carriage.High S/N Ratio(90dB) ensure cleanest voice transmission. Long-Lasting Power,both transmitter and receivers are built-in 900mAh lithium upgraded battery to guarantee more than 18 hours working.One transmitter could pair up countless receivers as long as they are on the same frequency.Transmitter has 3.5mm input jack, it supports AUX( such as MP3, Smartphone,MP4,CD etc) and MIC (microphone )input. The wire of microphone and ear