Features: One end is connected to the instrument audio port, the other end is connected to the sound system, transmitting audio signals wirelessly. Equipped with USB charging cable, two Micro USB plugs, transmitter and receiver can be charged at the same time. There are four channels, up to four systems can be used simultaneously, the signals won't interfere with each other. Indicator light of transmitter: At boot, the indicator light will indicate the channel number according to the corresponding flashing times of channel. Later, the red light keeps on, with being in transmitting state. Indicator light of receiver: At boot, the indicator light will indicate the channel number according to the corresponding flashingtimes of channel. Package List:1 * Transmitter1 * Receiver1 * USB Charging Cable1 * Manual