DROK High Accuracy 2V Digital Voltmeter +/-0-1.9999V Red LED Voltage Tester 0.001V Resolution for Positive Negative Volts Measuring 5V Power Supply with Polarity Protection +/-1.9999V DC full measure range, 0.0001V resolution. it will show "H" if over- range. It can measur DC +5V +/-5% operating power supply with low current consumption. 0.56" red LED digital tube with bright clear voltage high accuracy reading. Selectable decimal point position, with calibration potentiometer. With polarity protection circuit, it will not be burnt if the power supply positive and negative are