Features:
1, Input voltage/ voltmeter range: DC 4.5~40V, (please input voltage 6.5 ~ 40V , then can get a 5.0V stabilize output)
2, Output voltage/current: 5V/2A
3, Voltmeter display can be calibrated
4, with reverse polarity protection, with over current, over temperature protection
5, with USB power indicator
6, high-efficiency, low ripple
7, Module dimensions: 58mm * 21mm * 10mm (L*W*H)
8, Net weight: 13g
Instructions Fur use:
After power-on, the voltmeter digital display, if need to charge phone,Tablet PC, MP3 , 
please press the "Output Enable" button, then the USB power indicator lights, USB output 5.0V; 
if need to turn off the digital display, please press "low power" button, then enter the low-power standby mode, USB output shutdown.
Voltmeter calibration method:
1, when the voltage meter display, press "Output Enable" button 2 seconds then release, voltmeter flashes.
2,Touch the "Output Enable" button, the voltage increases one unit, touch the "Low Power" button, 
reduce one voltage reduction unit(one unit is less than 0.1V )
3, After the voltage adjustment is completed, please press the "Output Enable" button Fur 2 
seconds then release, exit voltage calibration mode. if power off, parameter setting will automatically save.
Uses:
Car / motorcycle battery voltage monitoring, or other voltage measurements.
USB Charger Fur Mobile phone, MP3, Tablet PC or other electronic products.
Please Note: this module defaults to D+,D- shorted, compatible with most of the cell phone charging, 
if need to install identification resistor, such as IPhone please cut off the red line position
Package include:
1x DC/DC Converter Digital Voltmeter Display USB Charger