- No wire removal needed: test spark plugs, ignition coils, and high voltage performance without disconnecting wires. - Real-time ignition check: when the engine starts or runs, place the pen end on the high voltage line; LED flashes to indicate ignition performance. - Safe and reliable: insulated handle provides safe, reliable operation when testing spark plugs, coils, and breaker. - Accurate contact: grooved tip increases the contact area between wire and instrument for more precise test results. - Versatile compatibility: suitable for testing spark plugs, ignition coils, and breaker on compatible engines. - durable, high quality design: insulated handle built for repeated use in automotive and workshop testing. Use scenarios: - Car maintenance: diagnose ignition system performance on cars to verify spark plug and coil operation without removing wires. - Motorcycle or ATV diagnostics: quickly check ignition components with engine connected to the wiring harness. - After replacement testing: confirm new spark plugs, coils, or breakers are functioning correctly before finalizing repairs.