1. The tachometer is used on all gasoline engines, with spark plugs2. Inductive design, you only need to bundle the connecting wire for a few turns on the spark plug to work3. Timing range: less than 9999.9 hours; speed range: 15300RPM4. LCD liquid crystal display5. DC low voltage supply, built-in battery CR2450, DC3.0V6. The speed mode can be set, applied to 2-stroke or 4-stroke gasoline enginesName: TachometerColour:blackMaterial:plasticPackage Contents:2 x TachometerOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.