Hands-free calling: you can accept, hang up, reject a call or redial the last number without any problem. Enjoy Music: The FM transmitter can play music from Bluetooth devices via FM signals to the car stereo. It can also stream music from 32GB micro SD or U hard disk. Dual USB Charger: One is 5V/2.1A USB charging port which provides fast charging speed. The other USB port allows you to transfer music to the U disk. Excellent Sound Quality: With built-in high-performance microphone with echo and noise cancellation (CVC) to give you a smooth call and clear. Additionally, the next time the transmitter is turned on, it will automatically connect to its last paired Bluetooth device. Specifications FM Frequency Range: 88.1~107.9 MHz Working Voltage: 12-24V USB Charger Output: 5 V / 2.1 A (max) MicroSD card and USB memory slot Format: MP3, WMA MicroSD and USB flash disk (maximum capacity): 32 GB FM range: about 5 m Compatibility < br> The FM transmitter works perfectly with most Bluetooth devices such as iPhone, Huawei, Samsung, LG, HTC, iPad, etc. Properties With this wireless device, you can easily answer / hang up / reject / take calls with hands-free functionality. Bluetooth playback for devices with Bluetooth functionality, playback via USB flash drive, micro SD card slot. One is 5V/2.1A USB charging port, the other USB port allows you to transfer music to U disk. Package 1 x Transmitter 1 x User Manual