Linstore 86982 Engine Ignition Spark Tester Linstore's new product, sales from 2016-4-18~2016-5-18, welcome everyone to purchase this item Must-have diagnostic tool for any engine with a spark plug Connect the tool between the spark plug and the plug wire to test whether it has spark when engine won't work Turn the engine over - if ignition is being sent to the cylinder, light in tester glows Great time and frustration-saver with cars, motorcycles, boats, chainsaws, lawn mowers & more