Features Supply Voltage: DC 4.5-30V Measuring Range: DC0-100V Display Tube: Three 0.36" Digital LED Tube Refresh Rate: About 200mS/Times Accuracy: 1%(+/- 1 Digit) Working Temperature: -10 - +80° Display Color: Red/Green/Blue Description:-This voltmeter uses 0.36 inch digital LED tube without housing. The voltmeter is super thin with small shape and low price and stable performance. It can display well.-The measuring range of the voltmeter is wide, it is DC0-100V. It needs external working power supply and the voltage is DC4.5-30V. There is protection when the wires are not connected properly.-The display resolution of the voltmeter is 0.1V.-This voltmeter is suitable for customers who have DC power because it can save cost. And it can be used when the voltage needs to be measured from 0V.Precautions-The measuring range of the voltmeter is 0-100V, this voltage is only a measurement signal and cannot be considered as the working power supply of the voltmeter. -This voltmeter needs external working power supply, which can supply DC4.5-30V as working power supply. About three wires, the black wire is the common negative pole, the white wire is connected to the positive pole of the measuring voltage, the red wire is connected to the positive pole of the working power, the measuring circuit and the negative pole of the power supply circuit are common.-The voltage of this voltmeter working power supply is 4.5-30V,30V is the maximum limited working voltage of the voltmeter, please leave enough margin during operation to avoid permanent damage to the voltmeter due to electrical spark, power ripple or other over-high sudden voltage change.-This voltmeter did not perform moisture, waterproof, shock resistance, oil treatment, please be careful or operate by yourself when using. Package Included:1 X Digital Voltmeter