THREE CHOICES TO STREAM YOUR MUSIC Bluetooth FM transmitter can stream clear stereo music freely in 3 ways--A. The FM transmitter can Play music from Bluetooth-enabled devices to car stereo via FM signal; B. Stream music from SD card, supporting music files like MP3/WMA/FLAC/WAV/APE; C. Transmit music from USB flash disk (up to 32GB).2 USB PORTS & SAFE CHARGINGSupports charging 2 devices simultaneously with overcharge protection. One USB port(5V/1A) with music icon can read USB disk, another USB charging port(5V/2.4A) efficiently gets your smart device fully charged. Enjoy in-car stereo streaming and charge smart phones at the same time. HANDS-FREE CALLS With this wireless device, you can conveniently answer/ reject/redial calls through hands-free function and enjoy safe driving. Noise and wind will be suppressed by CVC technology, creating full duplex sound quality. AMBIENT RING LIGHT & LED DISPLAYWhen power on, the ambient luminous ring light will illuminate blue, making it easy to use in car dark environments, and also brings a cheerful atmosphere; Easy and comfortable to view volume, car voltage and FM frequency displayed on the LED screen.