When the engine is running it will display the engines RPM and when the engine is turned off it switches back to the hour meter after a few seconds.

Self-powered engine digital tachometer includes:

• Digital display of engine run time
• Tachometer included displays engines RPM
• Inductive Tachometer from spark plug lead 0-25,000rpm
• Easy installation, no battery, cutting or special tools required
• Compatible with any spark plug equipped engine
• Screws and double-sided adhesive included for mounting