Searon Multifunction Hour Meter Tachometer Voltmeter with Clock 2 & 4 Stroke for Small Engine Boat Outboard Mercury Motocross Motorcycle Lawn Mower Generator Multifunction hour meter tachometer voltmeter with Colck for gas petrol engine Record total running hours and partial time, Partial timing can be reviewed and reset. Display current RPM of engine. review Max RPM and over RPM reminder. Real-time display current Voltage. Internal CR2450 battery and External DC 10-30 volt power