Docooler&reg; DC 6V-50V 12V Hour Meter Gauge Hourmeter Tachometer for Small Engines Car Boat Rectangular The timer operates on in put voltages from 6 to 80 Volts DC. The meter has a positive and a negative lead for easy installation. It is designed to withstand vibration and shaking up to 8g. It is designed to withstand vibration and shaking up to 8g. Widely used for tracking time on machinery such as boats, cars, trucks, tractors or any other device where time is used to determine oil change intervals, service requirements or where there is a need to record hours operated.