Spark Plug & Lead Tester

Test both spark plugs and spark plug leads. With engine running place the wire in the cradle; slide it up and down the length of the wire. Flashes of light should be visible. To test spark plug; place opposite end as dose to spark plug boot as possible. Flashes of light should be again visible. Steady flashes indicate normal. Erratic or no flash indicates faulty component Length: 95mm (3.3/4")