[Receiver USB Mode]The usb mode does not need to use 3.5 audio cables. It can be directly plugged into the car usb interface and speaker usb interface, and can be used directly after pairing with the mobile phone.Note: The car usb interface and speaker usb interface must support usb audio output. [Receiver AUX Mode]AUX Mode needs to connect one end of the 3.5 audio cable to the kn318 audio interface, and the other end to the car 3.5 audio interface and speaker 3.5 audio interface, and it can be used after pairing with the Bluetooth of the mobile phone. [Bluetooth hands-free calling]Built-in microphone, when the mobile phone is talking, you can make hands-free conversation through the microphone on KN318, which is very convenient to use in the car. [Plug & Play] No configuration required.You can unplug the usb bluetooth dongle from the USB port and re-insert it to switch between the two modes.Easy Carrying and Space Saving. perfect for use on the go, the red light will flash during pairing and the red light will stop flashing after the pairing was successful. [Multiple Uses Transmitter Receiver]:Bluetooth adapter 5.1USB dongle can easily let your PC, computer or other devices to connect more wirelessly bluetooth devices, this bluetooth adapter have Transmitter & Receiver feature, implement wireless stereo music streaming.You can ur for headphones, speaker, receiver, mouse, smartphone, tablse Bluetooth adapteet, ect. product name:Bluetooth 5.1 Audio Receiver Adapter Model: KN318 Technologies: BT5.1, A2DP, AVRCP Operation Range: Up to 10m / 33ft Pairing name:KN318 Pairing: blue LED flashing Paired successfully: The blue light keeps on Colour: black Material: ABS Size: 32mm x 17mm x 8.5mm Package Contents: 1 x Bluetooth audio receiver 1 x 3.5 audio cable 1 x English manua