Features: The tachometer is used on all petrol-engines with spark plugs. Inductive design, only need to bundle the connecting wire a few turns on the spark plug to work. Timing range: less than 9999.9 hours; speed range: 15300RPM. LCD liquid crystal display, DC low-voltage power supply, built-in battery CR2450, DC3.0V. The rev-mode can be set for 2-stroke or 4-stroke gasoline engines. Package Includes: 1 x Tachometer 1 x Wire Specifications: Material:Plastic Size:Approx.7.35x4.67cm/2.89x1.83inch Color:Black note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thanks for your understandings.