This hour meter works on any gas engine & generator, such as marine, ATV, motorcycle, dirt ski... Could track the service life of your machine, plan for oil changes, valve, adjustments, clutch service, chassis lubrication, and other maintenance schedules. | Record and display to 9,999.9 hours. Stand-by time up to over 20,000 hours. Hour glass symbol appears and flashes on/off to indicate counting time. | Automatic roll over resolution 0.1 hour. 100% epoxy encapsulated, waterproof, shockproof, high temperature resistance. | Easy Installation: Connect the hour meter & spark plug with the wire, then use the screws or zip tie to fix the hour meter. | No battery required, just connect to spark plug wire.