This product is blue-tooth car charger mp3 player for vehicle . Adapting professional-grade high-performance bluetooth module ,built-in mp3/wma decoder chip make it capable of playing the music files in u disk,firing into the car stereo via wireless. Besides, during the bluetooth connecting, play the phone’s music and FM transmitter to Car Audio, perfect ,as the calls incoming automatically switches to the speaker state, call end then automatically back the music player. So you do not do any modifications, easily enjoying the music and handsfree phone calls while you are driving. 1 This product is dual USB output. You can charge two devices at the same time ,the maximum output is 5V / 2A. 2. Insert U Disk ,only the one usb Port(the number 10) support. 3: LINE and insert U disk and Bluetooth turned on, then boot priority Bluetooth connection; When the Bluetooth connection on and then insert U disk / LINE, the latter takes precedence. 4 when the machine in FM transmitter ,volume will not be too much (generally 25 or less position) in order to avoid sound distortion, adjust the volume using the car stereo adjustments. 5. The machine FM transmitter built-in antenna, while also should try to avoid using strong local radio frequency signals to get better sound quality. 6. Due to various differences in the phone itself, the method used in the Bluetooth may be different in practice. 7. In the player again after power off, and some mobile phones may not automatically connect function, so need to use a manual connection again. 8. Although this product is compatible with more than 95% of the current market major brands mobile phones, but there are still some phone are not compatible, in the purchase process please note. 9. During a call, adjust the volume to moderate, not too big, so as not to affect each other's call quality. 10. Do not use this product in a particularly high or low temperatures and dusty, humid environment. 11. Do not let the product fall for avoiding surface and body damage.