Dual USB car charger: 2 USB charging ports to charge most USB Devices. Input 12V/24V. 1.0A USB port can read and charge function; smart 3.1A charge port that can intelligently identify Android or iPhone devices and charging.More compatibility: Wireless Bluetooth FM transmitter adapter for car radio, transfer calling/MP3 Music/Cellphone voices to the car speaker.Compatible with iPad,iPhone, Samsung, Google, LG, HTC, and Bluetooth devices. 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 of voltage when plugged into the car outlet port. Always keep the battery state health. Then it turns to automatic play mode. Music playing: Bluetooth cigarette lighter adapter for music 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 powered on.