Features:  Rated working voltage :12V~24V  Limit working voltage :8-27V  USB output Dual USB output Max:5V/3.4A   Charging identification USB2 support :5V/2.4A    Display:1.4” LCD Display  Degree of distortion:<0.1%  Frequency response:20Hz-15Khz  Left and Right Channel:>60dB  bluetooth-compatible version: Version 4.1+EDR  bt sound processing: A2DP (Advance Audio Distribution Profile) function supported  bt transmission distance: Barrier-free within 10M  Effective distance of bt microphone： 0.5-2 M  FM frequency：87.5-108.0Mhz      Description:  This device is a Bt Mp3 player for car-used, which  equipped with professional high-performance Bt  module and Mp3  decoder chip.  It can transmit the music from TF card to car stereo via FM radio signal.  It can transmit your mobile phone's music to car stereo via Bt.  It can also be used as a hands-free car kit during driving.  This device transmits signal by wireless method, no need to modify  anything in car. It can be used both as the music player in entertainment  purpose or hands-free car kit safety purpose during driving.      Product Introduction:  1. Support Bt hands-free phone calling via its build-in microphone.  2. Noise and wind suppressed by CVC technology to create full duplex sound  quality.  3. Support mobile's A2DP function. Music will be played directly while the  mobile phone is connected.  4. Mobile phone can be connected automatically when the device turns on.  5. Support an external TF card, can play music files in Mp3/WMA format.  6. Integrated car charger of output 5V-1500mA, is available for charging  handheld devices in car.       Package Includes:  1 x FM Transmitter  1 x User Manual(No Retail Box)