Item specification: Material: plastic Model: KN330/M135 Technologies: BT5.0, A2DP, AVRCP (receiver mode only) Operation Range: Up to 10m / 33ft (without any blocking objects) Pairing name(Receiver mode ): M135 Transmitter mode: red LED light is on Receiver mode: blue LED light is on Dimensions: 45 * 20 * 11mm / 1.77 * 0.79 * 0.43inchesMode switching: Use the TX/RX switch to switch modes.TX is the transmission mode(red LED).RX is the receiver mode(blue LED)There is no built-in battery, and it is powered by DC 5V USB interface Insert USB power, the red light is on in the transmitting mode, the red light flashes when pairing, and the red light is always on after the pairing succeeds. Insert USB to power on, the receiving mode is blue light, the blue light flashes when pairing, the blue light is always on after pairing is successful.Package Contents: 1 * Bluetooth 5.0 Audio Transmitter/ Receiver 1 * 3.5mm Aux Cable(1m/39in) 1 * User ManualNote:1.Light and monitor setting may cause slight color difference. 2.Please allow slight deviation as all dimensions are measured manually. The image is only for reference.Promise If the product has any quality problems, please feel free to contact us, we will help you solve the problem as quickly as possible.