✅1.  Bluetooth FM transmitter built in 10 functions:☑️1).Bluetooth Receive Mobile's Calls, Music, Google/Apple Maps Navigation Voice via Bluetooth and Wireless transmit the audio into car FM radio;☑️2). Bluetooth Receive Mobile's Calls, Music, Google/Apple Maps Navigation Voice via Bluetooth, then wired transmit the audio into car stereo via 3.5mm cable;☑️3). Wired Receive audio signal from Mobile; MP3/MP4 Player; CD/DVD player via 3.5mm cable then FM transmit this audio into car FM radio;☑️4). Play Micro SD Card's Audio file and Wireless transmit the audio into car FM radio;☑️5). Play Micro SD Card's Audio file, then wired transmit the audio to car stereo via 3.5mm cable.☑️6). Play USB flash drive's Audio file, then Wireless transmit the audio to car FM radio;☑️7). Play USB flash drive's Audio file, then wired transmit the audio to car FM radio;☑️8). Dual USB charging port:5V/2.1A smart and faster Car USB charger for all portable devices;5V/ 1A Car USB charger (Same with the USB flash drive port) for all compatible devices such as mobile☑️9). Car Voltage Measurement while the kit plugging in the car cigarette socket.☑️10. On/off switch function, press and hold multi-function button 5 seconds to active sleeping function if you do not use it(car charging function still work at this mode)✅2. Using Tips:☑️1). Press and hold the multi-functional button for 8-10 seconds to shift languages (English or Chinese);☑️2). Methods of eliminating noise:a).Try to turn mobile’s volume at maximum position, then adjust the car audio volume, the car maximum volume is not recommended. (this will bring lot noise).b). Connect a Ground Loop Noise Isolator before the car Aux in port.☑️3). Remove it after using.