Description: Car spark plug tester has two testing holes, you can test two spark plugs meanwhile and if you suspect any spark plug works improperly you could compare and test to make accurate judgment. Car spark plug tester usage can be shown: 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; connect to power supply; turn the key switch 4 clockwise to turn on tester, indicator 3 will light up, tester is now working at 1000rpm/min; again turn the key switch 4 clockwise,you can adjust the working frequency between 1000rpm to 5000rpm/min; the higher the frequency, the stronger the spark strength. There are some using warning notes. Firstly, turning off power before you place spark plug; Secondly, the spark plug tester is a high-voltage detector, so do not touch spark plug with hand at work to avoid danger. Car spark plug test principle can be shown. 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 detector could tell the good spark plugs from the bad by the strength of the spark. To test spark plug performance and ignition strength, it apply to 12V Gasoline vehicles car spark plugs. Made of high quality ABS and metal material, the spark plug tester is sturdy, durable, and wear resistance. The length of spark plug tester is 14.5cm, the width of spark plug tester is 8.5cm, the height of spark plug tester is 5.5cm. It is suitable for car, truck, motorhome, trailer, etc. Item Name: Spark Plug Tester Material:Plastic,Metal Input Voltage: 100-240V AC Output Voltage: 12V1A DC Plug Type: EU Plug, US Plug, UK Plug Size Details: Size: 14.5cm x 8.5cm x 5.5cm/5.71" x 3.35" x 2.17" (Approx.) Notes: 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. Package Includes: 1 X Spark Plug Tester 1 X Power Adapter