The dual-hole car spark plug tester has two test holes, allowing you to test two spark plugs at the same time. If you suspect that a spark plug is not working properly, you can compare and test to get an accurate assessment. Used to test the performance and ignition strength of the spark plug, suitable for spark plugs in 12V gasoline vehicles. Adjustable dual-hole car spark plug tester, glow plug analyzer, diagnostic tool Advantages of dual-hole car spark plug tester: The dual-hole car spark plug tester has two test holes, allowing you to test two spark plugs at the same time. If you suspect that a spark plug is not working properly, you can compare and test to get an accurate assessment. Purpose: to test the performance and ignition strength of the spark plug Scope of application: spark plugs for 12V gasoline vehicles. Automobile Spark Plug Test Principle: In a car's ignition system, a high-voltage ignition coil generates a high voltage (over 10,000 volts), which is converted into high-voltage electricity through the spark plug. The high-voltage ignition coil enters the engine cylinder, sparks are generated between the electrodes of the spark plug, and the mixture is ignited. The detector can determine the quality of a spark plug depending on the strength of the spark. Precautions when using the automobile spark plug tester: 1. Turn off the power before inserting the spark plug 2. The spark plug tester is a high-voltage detector. Do not touch the spark plug with your hands during operation to avoid danger. Car Spark Plug Tester User Manual: 1. Insert the spark plug into test hole 1 or 2. If you want to compare the new spark plug with the old spark plug, insert the new spark plug into hole 1 and the old spark plug into hole 2. 2. Connect the power supply 3. Turn the key switch 4 clockwise to turn on the tester, the indicator light 3 lights up and the tester runs at 1000 rpm. 4. Turn the key switch 4 clockwise again to adjust the operating frequency between 1000 rpm and 5000 rpm. The higher the frequency, the stronger the spark intensity. Product parameters of the spark plug tester for gasoline vehicles: L size 'host: 145*85*60mm Host weight: 220 G (excluding power adapter) Power adapter: 100-240 V AC input / 12 V 1 A DC output. The Spark Plug Tester for 12V Petrol Vehicles test set contains: 1 Spark Plug Tester 1 Power Adapter