About this item Dual USB car charger: 2 USB charging port to charge most USB Devices. Input 12V/24V, 1a port with USB reading and charge function; smart 3. 1 A charge port which can intelligently identify Android or iOS devices and charging. More compatibility: wireless Bluetooth FM transmitter adapter for car radio,transfer calling/MP3 music/Cellphone voices to car speaker.Compatible with iPad,iPhone,Samsung,Google,LG,HTC and Bluetooth Device. Hands free function: built-in microphone, switch to hands-free mode automatically from music playing status when receiving calls. Answer/reject/hand up/recall all in One key. Car battery voltage function: Show 3 seconds voltage when plug into the car outlet port. Always keep battery state of health. Then it turn to automatic play mode. Music playing:support Bluetooth /USB disk/TF card/ MP3/wma player. With anti-interference performance and CVC technology.Listening to music while charging. Automatically connect memorized paired when power on.