The Rock B302 FM transmitter has two USB charging ports, an LED display that indicates the FM frequency and battery level, and the ability to stream music from your smartphone using an AUX or Bluetooth cable. Music can be played from a USB drive or MicroSD/TF card. You can use your cables to charge two devices simultaneously. Convenient one-click call answering and an integrated microphone make it compatible with the majority of Bluetooth 5.0-capable devices.