1. Dual USB Charging Port. Charge two devices simultaneously. Max current output: 2.1A, provide fast charging speed. 2. 1.44 inches Screen can show incoming call number, voltage level in car battery, volume, FM frequency and song name if you play music from TF card or USB flash disk. 3.Hand-Free Calling and High Stereo Sound. 4. Four Playing Modes. A: Play music from Bluetooth-enabled devices via FM signal; B: stream music from TF card, supporting music files like MP3, WMA, WAV; C: transmit music from USB flash disk; D :stream music from your MP3 player, old speaker, tablet etc to the car stereo system via 3.5mm audio cable. Specification: Stand-by Current: 25mA (Max) Bluetooth Version: V3.0 + EDR Working Current: 45mA (Max) Effective Range: 5 meters Frequency: 87.5MHz 108.0MHZ Note: Please do not play music from two sources simultaneously, or there will be two voices. If you want to change mode to play music, pause the musicof the first source, and then play the music of the other source. Package: 1* FM Transmitter 1* 3.5mm Audio Cable 1* User Manual