Steren WR-906UHF Manual De Instrucciones página 33

11. If you want to mute the microphone, place the switch to Mute position,
the yellow LED keeps lighting.
12. Turn the system off after their use.
The indicator LED in the microphone will light up when the battery's energy
is almost empty, please replace the battery.
The distance between the receiver and the microphone won't be
more than 70 meters.
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