Function: 1 . The tester is designed to test spark plug performance and ignition intensity. 2. With 2 test holes, you can test two spark plugs simultaneously, which is very convenient. 3. With the indicator light, it can display the condition of the spark plug more intuitively and understand better. 4. Easy to operate, plug and play, no complicated steps, convenient and practical. 5 . If you suspect any spark plugs are not working properly, you can compare and test to make a careful evaluation. Specification: Item Type: Spark Plug Tester Material: ABSMetal Black colour Plug: 100-240V US plug Spare adapter plug: EU 125-250V plug Size: Approx. 140 x 80 x 40mm / 5.5 x 3.1 x 1.6 inch (There may be 1-2mm deviation due to manual measurement) Application: 12V gasoline car spark plug Product Feature : Spark Plug Tester: The two hole automotive spark plug tester has two test holes, and can test two spark plugs simultaneously. If you suspect any spark plug is not working properly, you can compare and test to make a thorough evaluation; What is the role of a spark plug? The job of the spark plug is to inject tens of thousands of volts of high voltage into the combustion chamber and generate electric sparks to ignite the mixture. Use with ignition and fuel systems to keep the engine running normally, which largely determines the performance of the engine. Spark plugs are everyday consumables for cars. The performance of the spark plug, which is the core of a car engine, can almost directly affect the performance of the car, so always check the spark plug of your car. How to use: check the operation of the spark plug and the intensity of ignition. Car spark plug tester operating instructions (see photo): 1 . Insert spark plug in ① or ②. If you want to compare the new spark plug with the old one, insert the new spark plug in hole ① and the old spark plug in hole ②. 2. Connect to power 3. Turn the knob ④ clockwise. After switching on the power, the warning light ③ comes on and the tester is now running at 1000 rpm. 4. Continue turning knob ④ to adjust the operating frequency between 1000 rpm. /min up to 5000 rpm /min. The higher the frequency, the higher the spark plug power. Package List: 1 x Spark Plug Tester 1 x Power Cable 1 x Spare Adapter Plug Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.