Premium tools to get the job done right. Spark plug misfires occur when the sparks jumping the electrode gap are inconsistent in timing, causing the engine to stumble or lose power. Heavy-duty construction. Made from materials chosen to reliably test whether your spark plug is functioning correctly. Saves time and money by confirming whether the ignition is the actual source of the problem. Compact and handy. This tool lets you view the spark plug tester gap to determine if you have inconsistent timing or not. Durable ignition tester. Constructed from high quality materials and designed to work on spark plug connections. Diagnoses spark or spark failures, defective contact points, bad wiring, and more. 2-3 practical use scenarios: - Diagnose engine hesitation or loss of power at light or high load to determine if the ignition timing is at fault. - Check a new spark plug before installation to ensure it functions properly. - Verify after replacing ignition components (plugs, wires, coils) that the ignition system is delivering a consistent spark.