This is mini voltage tester is high in precision and easy to use. It has large testing range 0-30V and reversed polarity connecting protection， very safe and convenient to use widely in many circumstances. Even if you're a green hand， you can apply it to test voltage.Features:High Precision: test and display voltage to 5 digits.Large Testing Range: 0-30V to better suits your needs.Variable Precision: precision will automatically change when the voltage is below 4.3V and the highest precision is to 0.1mV.Flexible Power Supply: No need of isolating power， it can use the system common ground.Have the reversed polarity connecting protection to prevent the damage of voltmeter..Mini Appearance: portable and convenient to use in many circumstances.Specifications:Color: BlackData Display: LED ScreenVoltage Testing Range: DC 0-4.3000-33.000VPrecision: 5 DigitsRefresh Speed: > 3 times/secondTesting Accuracy: ±(0.3‰ + 2 bytes) (means that the biggest error is within 10mv， normal error is within 2mv)Power Supply: DC 3.5-30V Working Temperature: -10℃-65℃Cable Length: 14cm / 5.51inItem Size: 4.7 * 1.7 * 2.5cm / 1.85 * 0.67 * 0.98inItem Weight: 16g / 0.57ozPackage Size: 5 * 2 * 3cm / 1.97 * 0.79 * 1.18inPackage Weight: 16.5g / 0.58ozNote:1. Red line + : Positive Electrode Black Line -: Negative Electrode (For Power Supply) Red line VIN: Positive Electrode of Testing Signal Black Line VIN: Negative Electrode of Testing Signal2. This voltmeter needs independent power supply. When it is connected to power supply， it will display 0.0000 ( if it is hung， it will show 0.0001-0.0002).Package List:1 * Voltmeter