Description: Professional Tool: Test the ignition system of your car with this Spark Plug Tester Double Holes, ensuring optimal engine performance For Mechanics: This Spark Plug Tester is a must-have tool for automotive professionals, allowing for quick and accurate diagnosis of engine issues Easy to Use: The Spark Plugs Automotive Engine Ignition Coil Tester is designed with double holes for testing both regular and irregular spark plugs easily Efficient Performance: This Spark Plug Tester provides a reliable way to check the ignition system, saving time and money on unnecessary repairs Durable Construction: Built to last, this Spark Plug Tester is made of materials to withstand frequent use in a workshop or garage setting Specification: Name:Spark Plug Tester Double Holes Material: Plastic + Metal Usage: Test spark plug performance and ignition strength Application Range: 12V Gasoline vehicles car spark plugs Widely Application: 100V-240V input voltage . JF109 Spark Plug Test principle: In automobile ignition system, the high-voltage ignition coil generates a high-voltage (10000 volts or more), and the spark plug diverts it form high -tension ignition coil into the cylinder engine, spark between the spark plug electrodes will ignite the mixture. The JF109 could tell the good spark plugs from the bad by the strength of the spark. JF109 Spark Plug Tester Using Note: 1. Please Turn Off Power before you place spark plug 2. The Spark Plug Tester is a high-voltage detector, so do not touch spark plug with hand at work to avoid danger. JF109 Spark Plug Tester User Manual: 1.Place the Spark Plug into tester hole 1 or 2; If you want to compare the new spark plug and old one, place new spark plug into hole 1 and the old on into hole 2 2.Connect to power supply 3.Turn the key switch 4 clockwise to turn on tester, indicator 3 will light up, tester is now working at 1000rpm/min. 4. Again turn the key switch 4 clockwise,you can adjust the working frequency between 1000rpm to 6000rpm/min.The higher the frequency, the stronger the spark strength. Package Includes: 1 x JF109 Spark Plug Tester Main Unit 1 x Power supply connector 1 x Gasket 1 x User manual