Features: 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;  Transmitter mode：wirelessly streams audio from your non-Bluetoo TV, home stereo system, or CD player to your Bluetooh headphones or speakers;  Receiver mode：wirelessly streams audio from your Bluetoo-enabled phone, tablet, or computer to your wired stereo, speakers, or headphones;     Mode switching: a) First plug the product into the USB port to power on;  b) When the time after power-on is within 10 seconds, you only need to re-plug once to switch modes;  c) When the time after power-on exceeds 10 seconds, you need to re-plug twice to switch modes;  Model: KN320;  Technologies: BT5.0, A2DP, AVRCP (receiver mode only);  Operation Range: Up to 10m / 33ft (without any blocking objects);  Pairing name(Receiver mode ):KN320;  Transmitter mode: red LED light is on;  Receiver mode: blue LED light is on;  Dimensions: 32mm x 17mm x 8.5mm;     Note:  This product has been used for more than 10 seconds and will remember the mode. It will be the last mode when it ispowerd on next time.    Package Included: 1 x Bluetooh 5.0 Audio Transmitter/Receiver Adapter;  1 x 3.5mm Aux Cable;  1 x User Manual;