Metal chassis digital 900MHz wireless microphone receiver very reliable and easy to use. It is supported by a professional technical team. Use the volume up/volume down button to adjust the volume level (0 to 15) under lock status for receiver volume setup. For channel setup, unlock by pressing the “lock” button for two seconds till the lock icon disappears from the display. Press the “channel up” or “channel down” button to change the channel number. The receiver will auto-lock several seconds after setting/press and hold “lock” button for two seconds to return to normal mode. Microphone receiver features color TFT display, 1/4” combo unbalanced output, 902.000 to 928.000MHz frequency, 20Hz to 15kHz audio frequency response, 80dB S/N ratio, 9V power adapter and audio mute when signal lost. There are 12 channels available on this system which can work simultaneously.