Ignition spark tester: This connects between the spark plug and ignition lead to give a clear indication of the ignition system function.
Generator Guru says:
It is not uncommon for customers to replace an ignition coil only to find it was the spark plug being faulty. Connect the Ignition Spark Tester, turn over the engine and you will know instantly if the spark plug is faulty.
Works with all spark plugs.
A must have for the professional Mechanic.