Ancel Car Spark Plug Tester Ignition System 220V 110V Automotive Spark Tester Double Hole Detector Spark Plug Diagnostic Tool ANCEL Car Spark Plug Tester is for testing the performance and strength of spark plugs. The product simulates actual engine conditions and works up to 6000rpm. It is compatible with all spark plug tests for crankshaft engines and motorcycles on the market. It can also test two holes at the same time and is designed with a protective cover to ensure the safe operation of maintenance personnel during the test. Product Usage: 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.Note:This link is for 110V/220V power supply US PlugIf you need to buy 110V/220V EU PLUG, please note the information of