HONBAY DC 3-30V Digital Voltmeter Voltage Tester Gauge Green Bright LED Display 3 Wires Volt Meter for Solar Battery Monitor Car Motor Panel Mount (Green LED) Its decimal point will automatically move, and It also has a tiny potentiometer to do finer adjustments It only has 3 wires, the red connects to positive and the black connects to negative With reversed connection protection, it will not be burnt even when connected reversely, but the screen display nothing Large screen and bright LED display, and it is well made, the strong plastic case prevents it from easily damaged by outer force It is perfect to monitor the condition of the battery, especially for solar projects, you can use it on your car, trailer, motor, etc.