Description:-The wiring of the voltmeter is simple, you just need to connect two wires, the red wire is connected to the positive pole, the black wire is connected to the negative pole.-There is protection, when the wires are not connected correctly, the electric circuit will not be hit.-This voltmeter does not need the working power external disk, it can work with the measuring voltage, the working voltage range is 4.5-30V.-To achieve the best measurement accuracy, The voltmeter will automatically move the decimal point position according to different measurement voltage. When it measures voltage below 10V, it will display two decimal places. When it measures voltage above 10V, it will display one decimal place.-This voltmeter can be used to measure the battery voltage of motorcycles and cars, and it can also capture the condition of the battery. It can also be used to measure other voltage. Specifications:Measuring range: 4.5-30VDallowable error: accurate to 0.01V below 10V, accurate to 0.1V above 10V, 1% error allowed (+/-1 word)Display mode: 3-digit 0.56 & prime;& prime; Digital LED Tube Display Temperature: Red/Green/Blue (Optional)Refresh Rate: About 200mS/TimePower Supply: Not RequiredCurrent Consumption: Less than 20mA, Generally 5-15mATowing Temperature: -10°c - 65°c Dimensions: 48x29x16mm/1.89x1.14x0.63inch Hole Size: 46x27mm/1.81x1.06inchWire Length: 20cm/7.9inchPrecautions:30V is the maximum limited working voltage of the voltmeter, please leave enough margin during operation to avoid permanent Voltmeter damage due to electrical spark, power ripple, or other excessively high sudden voltage changes. Package Included:1pcs Digital Voltmeter