【Designed for 12V Gasoline Spark Plugs】This spark plug tester works by testing the performance of the spark plug by simulating engine operation. It is suitable for most spark plugs in 12-volt gasoline cars (12mm diameter) and motorcycle spark plugs. NOTE: Supports conventional spark plugs, does not support NGK spark plugs. 【Dual Test Holes】The spark plug tester can compare the intensity of the spark plug, evaluate the power and ignition strength of the spark plugs, and replace defective spark plugs in time. The spark plug tester ignition system has two spark plug connectors; you can compare and test them to make an accurate judgment at the same time. 【Working Frequency 0~6000 RPM】The spark plug tester is easy to operate, and you can use it directly after connecting the adapter. You can adjust the working frequency within a range of 0~6000 RPM. The spark plug tester can also simulate engine operation and restore car starting, providing better spark plug testing. Supports conventional spark plugs, but not NGK spark plugs. 【Safety and High Quality】For safer use, the device is equipped with a transparent protective cover. Cover the protective cover before use to ensure the safety of the operator during testing and observation. Visually displays the test results. Made of durable ABS material, which has impact and heat resistance. Lightweight and portable, it can be placed in a repair kit for extended periods.