Simply connect the tester between the spark plug and the plug wire, if spark is being sent, the tester will mirror the spark and light up - Find dirty spark plugs, defective points, bad cables or connections, etc.
Inline Spark Plug Tester Versatile Spark Plug Light Checker
2 Pcs Inline Spark Plug Tester, Plug Engine Ignition Tester, Auto Motorcycle
Inline Spark Plug Tester, Plug-in Engine Ignition Tester, Car Exterior Access...
Inline Spark Plug Tester, Plug-in Engine Ignition Tester, Car Exterior Accessor
