Check the listing for details. 0.28 Inch Two-wire 2.5-30V Digital Green Display DC Voltmeter Adjustable Voltage. Condition: New. Listed at 3.59 USD. Features:1. The wiring of this voltmeter is simple. The conventional two wires are used, the red is connected to the positive, the black is connected to the negative, and the reverse connection is protected.2. Conventionally, no external working power supply is required, and the measuring voltage can be directly operated. The measuring voltage range is two-wire 2.50-30V, three-wire 100V.3. Wide voltage operation, red 2.50V low and safe pressure up to 40V, more than 40V may be damaged.4. When measuring voltages below 10V, two digits are displayed after the decimal point; when measuring voltages above 10V, one digit is displayed after the decimal point. Measuring rangeTwo-wire DC2.50~32.0V / three-wire DC0-100V / 500VPower supply rangeNo need to supply power separately. The measured voltage 10V error ±0.1V; 50KΩWorking current