The Bike-It Ignition Spark Plug Tester is a handy tool that shows a duplicate view of the ignition spark.Ignition System 'Trouble Shooter'Quick And Easy To UseHands Free Device That Connects In-LineThis ignition spark plug tester from Bike-It is a quick and easy ignition system 'trouble shooter'. A 'hands free' Device that connects in-line between spark plug and lead showing a duplicate view of the ignition spark. Allowing you to visually check the condition of the ignition system at each cylinder. Frequency and intensity of the flash indicates whether there is an ignition system problem or a fault in the fuel delivery system. Flash can be seen in bright sunlight. Encased in a robust clear plastic body able to withstand rough use and resistant to automotive chemicals.