2 Usb Ports Safe Charging: Supports charging 2 devices simultaneously with overcharge protection. One USB port (5V/1A) with music icon can play USB disk, one other USB charging port (5V/2.4A) charges efficiently your smart device. Enjoy stereo streaming in the car and charge smartphones at the same time. Hands-free Calling: Built-in microphone with echo cancellation and noise suppression (CVC) technology, this car bluetooth transmitter provides amazing hands-free function; Answer/reject/hang up/redial calls all in one single multi-function button; Automatically switch to hands-free mode from music playing status when incoming calls. Blue Ambient Light: When powered on, the ambient light ring lights up blue, which makes it convenient to use in dark environments in the car, and also brings a happy atmosphere. Easy and comfortable to see the volume, car voltage and FM frequency displayed on the LED screen. Wide Compatibility: This FM transmitter works well with iPhone, iPad, Samsung, HTC, Sony, tablet and other Bluetooth-enabled devices such as MP3, MP4 Player. It also fits all cars/trucks (12-24V).