... speaker has Low wireless cost, Transmitting distance up to 100feet(max) Indoor/outdoor wireless speaker Features: 1 ... the classroom of 50-80 persons , distance up to 100feet(max) can receive the signal. 5. Wireless ... 6. Has the functions of audio output, input,high and low volume ,digital echo 7.A group of out ... use at night.Simply connect the transmitter to any audio device with an output jack using the ...