Feature:  1.This equipment can detect battery’s voltage.  2.Support Bluetooth hands-free calls, built-in microphone, secure answer calls.  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 powered on.  5.Support an external TF card / U disk, can play music files in MP3/ WMA format.   6.Integrated car charger of output 5V/3.1A, is available for charging handheld devices in car.     Specification:  Bluetooth Version: V3.0+EDR.  Limit Voltage: 9V-36V.  Rated Working Voltagae: 12V-24V.  Sensitivity: -42db+/ 3 db 360.  Voltage: 5V+ / -0.5.  Working Current: 45mA(max).  Stand-by Current: 25mA(max).  Frequency: 2.402-2.480 ghz.  Bluetooth Effective Range: 10-15 meters.  Sensitivity: -92 dBm.  RF Output: 4 dBm.  FM Frequency: 87.5MHz-108.0MHz.  Transmitted Power: 87dBuv / 107dBuv.  Microphone Effective Range: 2 meters.     Package Included:  1xCar Charger