Three wires digital voltmeter, mini size, portable and useful.With reversal protection, safe to use.Measure voltage range 0-30V, need DC4-30V external power supply.Type: Digital VoltmeterMeasure Voltage Range: DC 0 - 30VInput Range: DC 4V-30V (Max. Input: DC 30V. The device can be damaged if input is over 30V.)Measurement Accuracy:1%Display: Three Digit 0.56" LEDDisplay Color: Red, Green, BlueOperating Current: Red Refresh Rate: about 300mS/TimesPower Supply: Red: DC 4.5-30V, Green: DC4.7 - 30V, Blue: DC5 - 30VOperating Temperature: -10C to +65CFeatures: Useful, Mini, LED Display, Voltage MeterSize (L x W x T): 48mm x 29mm x 22mm/1.89" x 1.14" x 0.87" (Approx.)Lead Length: 20cm/7.87" (Approx.)Wiring:Red Wire: Power Supply +Black Wire: Power Supply -, Measure -White Wire: Measure +Notes:Due to the light and screen setting difference, the item& 39;s color may be slightly different from the pictures.Please allow slight dimension difference due to different manual measurement.Package Includes:1 x Digital Voltmeter