Fast and easy to use - flashing bulb indicates ignition or fuel delivery problem. Safety orange color for easy visibility. Provides information not available with OBD II code reading devices. Flash can be seen in bright sunlight - saves time and money as technician does not have to swap ignition coils. Clear plastic body can withstand rough use and resists automotive chemicals - shows a duplicate view of the ignition spark The one Ignition Spark Checker for troubleshooting virtually all domestic and imported cars, SUV's and trucks. Can also be used to test conventional and coil-on plug ignition systems. A must for new vehicles with recessed spark plugs.