It has a powerful timing system, RPM measuring system as well as some other function design. Timing System Including: accumulating total running hours TOT, recording partial running time PAr,Partial timer is resettable, etc. RPM Measuring System Including:measuring current engine RPM,recording MAX RPM 5s after engine stopped, RPM refresh rate 1S ,etc Design Including: easy installed,waterproof Rate IP68,etc. This tach hour meter record gasoline engine's total running hours and partial time by the induction from spark plug cable.The hour meter shows total hours and partial time accumulated. Partial timing can be viewed and reset . Model Name: HM016R Item Weight: 65g Special Features: hour meter/timer/counter It can work on most 2 or 4 stroke gas engine. The tach hour meter shows current RPM's and total running hours when the engine is running. RPM accuracy is 10RPM. Compared with the tachometer with pointer, it displays RPM more accurate. What's more outstanding is that the tach hour