This voltmeter uses 0.56inch LED digital tube and partially closed ABS plastic casing without rear cover. The voltmeter is super thin with small shape and low price and stable performances. It can display well.This voltmeter's measurement range is wide, It need outer working power supply and the voltage is DC4.5-30V. There is protection when the wires aren’t correctly connected.To reach the best measurement accuracy,this voltmeter will automatically move the decimal point's position according to the different measuring voltage.  This voltmeter is suitable for clients who has DC power supply,because this can save cost. And it can be used when the voltage need to be measured from 0V.  

1.)This voltmeter's measurement range is just measurement signal and it can't be regarded as voltmeter's working power supply. This voltmeter need outer working power supply which can supply DC4.5-30V as working power supply. About three wires,the black wire is communal negative pole,the white wire is connected to measuring voltage's positive pole,the red wire is connect to working power supply's positive pole,the measuring circuit and power circuit's negative pole are communal.   

2.)The voltage of this voltmeter's working power supply is 4.5-30V,30V is the voltmeter’s maximum operating limited voltage,please leave enough margin when working,to avoid voltmeter’s permanent damage because of electrical spark,power supply ripple,or other too high abrupt change of voltage.

3.)This voltmeter didn’t do moisture-proof,waterproof,shockproof,anti-oil processing,please be careful or handle by yourself when using.