?? Great Digital Tach ??It used on any 2 or 4 stroke gas engine up to 16 cylinders to record the RPM ,Maximum RPM recorded for last operation activity; RPM range: 0 to 25000.the refresh rate at 0.5s or 1s . ?? Engine Tachometer rpm ??To get an accurate reading,it sparks every other revolution. But with the ignition system on these engines, every time the flywheel makes one revolution, it passes the coil and creates a spark. That would be great if this were a 2-stroke engine, Trust me, this is how you’ll get an accurate reading with this tach on this type of engine. ?? Hour Meters Timing ?? Maintenance reminder cumulative total running time, Programmable Countdown tracking service reminder time; record part of running time JOB and JOB2, used to measure the time of a particular work job, Like change oil Air filter Replacement,maintenance timing ?? Diagnostic Engine Tachometer ??Timing analyzer how many hour you put on your engine.Whether the engine is turned off or on,display shows total run tim