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. Specifications: Condition: Brand New Material: Plastic + Metal Color: Black Channel: 4 Frequency Response: UHF System Frequency Response: 20Hz~20KHz Frequency: 730 MHz Max. Transmission Distortion: <50m(no obstacle) Latency: <4ms Power Supply: 3.7V/600mAH Built-in Li-battery & USB Cable Charging Time: <2 hours Work Hour: 4~6 Hours(full recharged) Size: Approx. 11 * 4.3 * 1.7cm / 4.30 * 1.68 * 0.66in Weight: Approx. 269 g Package List: 1 * Transmitter 1 * Receiver 1 * USB Charging Cable 1 * Manual Note: Due to different production batches, t he power switch has two modes (push up / push down to open).