Are you thinking it's time to check your RPM? Your truck's RPM could be fluctuating which could point to a mechanical or fuel-system issue, such as bad sensors or fuel pressure problems. A tachometer is a diagnostic and monitoring tool that helps you make sure your engine is running in a healthy RPM (Revolutions Per Minute) range. You're able to see much your RPM is changing, catch patterns, and see if your engine improved after repairs. how 

The ISSPRO 3-3/8" Programmable Tachometer is a precision RPM gauge designed for broad compatibility and easy setup. It can interpret RPM signals from virtually any standard source, including ignition coils, electronic ignition systems, magnetic pickups, pulse generators, Hall-effect sensors, and alternator AC outputs.

Its major strength is flexibility, featuring an extensive calibration window ranging from 0.1 pulses per revolution all the way up to 255 pulses per revolution. Settings can be fine-tuned in 0.1-pulse increments up to 25.5 PPR, allowing accurate configuration for almost any engine or sensor arrangement. A built-in peak-RPM recall lets you check your highest recorded RPM whenever needed. It operates on 9–32V electrical systems and is built to withstand tough conditions, offering transient protection up to +100V / -400V. The bright, long-lasting LED backlight provides excellent visibility, and the large 3-3/8" diameter face makes the gauge easy to read at a glance.