Features:
1. The wire connection is simple, only need to connect two wires, the red line connect the anode, the black line connect the cathode. Inside the voltmeter, there are reverse polarity connect protection.
2. This voltmeter work without external power supply, can use the measuring voltage directly, Wide working voltage range of 4.5-30V
3. For best accuracy of measurement, depending on the measuring voltage, the voltmeter automatically move the position of the decimal point. when voltage is below 10V, it shows two decimal places; when voltage is over 10V, it shows one decimal place.
4. The voltmeter can be used in motorcycles, cars etc monitoring battery voltage, grasps the battery state timely. can also be used for other voltage measurement purposes

Specifications:
Shape size: 48 X 29 X 16mm
Measuring range: 4.5-30V
Hole size: 46 X 27mm
The minimum input: DC4.5V(Less than the minimum voltage, measurement inaccuracies or display)
Wire length: 20cm
The maximum input: DC30V(Higher than this voltage, in danger of burning out)
Net weight: 17g
Gross weight: 22g(Package included)
Display method: three-digit number 0.56in LED Nixie tube
Display color: Red, green, blue optional
Update rate: about 200ms/time
Power supply: No need
Current consumption: Less than 20mA, normally 5-15mA
Working temperature: -10~65℃

Note: 
30V is this voltmeter maximum limit voltage, please keep enough allowance for table, to avoid permanent damage to the voltmeter due to spark of motor, power ripple and other mutations voltage

Included:
1 X Digital Display Voltmeter