Features:The wiring of this voltmeter is simple, you just need to connect two wires, the red wire is connected to the positive pole, the black wire is connected to the negative pole, there is protection when the wires are not connected properly, the electrical circuit will not be impactedThis voltmeter does not need working power to the external disk, it can work with the measuring voltage, the operating voltage range is 4.5-30VToreach the best measurement accuracy, voltmeter will automatically move the decimal point position according to different measuring voltage, when it measures voltage below 10V, it will display two decimal places, when it measures voltage above 10V, it will display one decimal placeThis voltmeter can be used to measure the battery voltage of motorcycles and cars, and it can also grasp the battery status, it can also be used to measure other voltageNote:30V is the maximum limited working voltage of the voltmeter, please leave enough margin during operation to avoid permanent damage to the voltmeter due to electric spark, power ripple, or other excessively high sudden voltage changesThis voltmeter was not moisture-proof, waterproof, shockproof, anti-oil, please be careful or operate by yourself when using Specifications:Measuring range: 4.5V-30V DCMimum input: DC 4.5V Maximum input: DC 30VDaccuracy: 1%(+/- 1 word)Display Type: 3 x 0.36" LED Tube Color: Red/Blue/Green Refresh Rate: About 200ms/time Current Consumption: Less than 20mA, Usually 5-15mA Working Temperature: -10°C - 65°C - 65°C Measurements: 34x23x1 7mm/1.34x0.91x0.67" (LxWxT)Hole Size: 30x2 0mm/1.18x0.79" Quantity: 1 PcNote: Please allow 1-3mm error due to manual measurement. Pls make sure you do not mind before you make a bid, due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!Package Included:1 x Digital LED Display Voltmeter