Description:Spark Plug Tester in Line for Automotive Car Lawnmower Must have diagnostic tool for any engine with a spark plug. Simple to use just remove rubber boot from spark plug, insert tester & place tester boot on plug. Turn the engine over if ignition is being sent to the cylinder, light in tester glows.How to useWith engine off remove spark plug wireAttach black connector spark plugInsert metal end of tester into spark plugTry to start the engineIf ignition circuit is complete, bulb will flashPackage Included:1 x Spark Plug TesterNote: This is Non original aftermarket Replacement Parts, please check the size and the pictures carefully for Compatible with before ordering it.Package Including4 * Accessories