Introductions: This product is bluetooth car charger mp3 player for vehicle with built-in Microphone. Adapting professional-grade high-performance bluetooth Module, built-in mp3/wma decoder chip make it capable of playing the music flies 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 calling incoming automatically switches to the speeaker's 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. Note: This item is not only support Bluetooth Handsfree phone Calling but also Bluetooth Stereo Music playing! Rated operating voltage: 12V Car Charger for most mobile phones Working voltage limits: 9-26V USB output: 5V/2A Support play format: MP3 WMA SNR: >60dB Distortion: <0.1% Frequency response: 20Hz-15Khz BT version: Version 5.0 Bluetooth transmission distance: 10M-15M Bluetooth microphone effective range: 0.5-2M FM transmission frequency: 87.5-108Mhz FM transmitter mode: Stereo digital PLL locking Features: -100% brand new and high quality -Adjustable to any angles -Full frequency FM transmitter -Digital display -Supports line audio input -With power off switch(USB direct connect) -Supports U Disk player -Supports MP3,WMA format music -Bluetooth answer, hang up, reject, redial calls and other functions -Bluetooth stereo music play -Supports dual USB output voltage, the maximum output 5V/2A -Automatic power-off memory function Package Include: 1* FM Transmitter