Special design: You can check sparks without starting the engine with our spark plug tester. It is designed to determine coil voltage and prevent high energy spark plug leakage. Ease of use: Simple to operate, the tester features a round knob for easy gauge adjustment. Use it to quickly diagnose ignition, engine problems and defects. Read easily: High visibility white font makes readings easy, with a measurement range of 0-40k deviation. Wide applications: Standard spark plug tester suitable for small engines and some motorcycles, lawn mowers, chainsaws, trimmers, snow blowers, etc. The plug wire end can be unscrewed. Use scenarios - Before seasonal maintenance on a lawn mower, test the spark plug and coil to verify proper ignition. - Diagnose ignition issues on a small motorcycle or chainsaw to determine if the coil, plug, or wiring is faulty. - During routine maintenance, check multiple spark plugs to identify those with leakage or abnormal performance.