Hour Meter - TOOGOO(R) DC 6V-50V Hour Meter Hourmeter Gauge for Boat Car Truck Engine Rhombus Black The timer operates on in put voltages from 6 to 50 Volts DC. The meter has a positive and a negative lead for easy installation. 6 digit display. 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. It is designed to withstand vibration and shaking up to 8g.