LCD Cigarette Lighter Voltage Digital Panel Meter Volt Voltmeter Monitor for Auto Car Truck Brand new and high quality. Color: black. Screen digital color: red. Installment: insert the jack of the product into a cigar socket. This digital gauge displays the voltage of batteries in the car. With high brightness of LED there is no difficulty in seeing the display. Powered by car cigarette lighter charger. Constantly monitor battery voltage, extend and protect the battery and engine life. Installment:Clean the Cigar socket. Insert the jack of the product into a Cigar socket. Attention:For DC 12V OR 24V CAR. Measuring range:DC 8V-30V+/-%1.2. What kind of batteries is healthy. When engine running(do not drive), the LED display:. Between 13.5 to 14.5 (12V Car). Between 26.0 to 28.0 (24V Car).