The Cal-Van Tools Magnetic Field Indicator, No. 82000, can immediately verify if an ignition coil is active or inactive by simply placing the tip near the coil. If the indicator detects a magnetic field, a blue LED will clearly illuminate. It can be used to diagnose electrical solenoid valves and test coiled relays, and it can even check audio speaker magnets. It also includes an integrated tester magnet to ensure the device is always working. The test tip includes a built-in LED flashlight.