Features: Comes with two test holes, you can test two spark plugs. Design for testing spark plug performance and ignition resistance. Apply to 12V petrol vehicles. Plug and play, convenient and easy to use Durable and reliable. Specifications: Power Supply: Input 100-240V AC; Output 12V 1.5A DC Main unit weight: 190G (without AC adapter) Dimension: about 145*85*60mm Detection port: 2 pieces How to use: 1. Insert the spark plug into test hole 1 or 2. (Note: If you want to compare the new and old spark plug, put the new spark plug in hole 1 and the old one in hole 2.) 2. Plug the power adapter into the socket under the host. 3. Turn the knob clockwise. After turning on the power, the top indicator light will be charged. At this time, the indicator 3 lights up and the tester is now working at 1000 rpm. 4. Turn the key switch 4 clockwise again and the frequency reaches 2000 to reach the ignition state. The higher the frequency, the higher the intensity of the spark plug. (Note: the higher the frequency, the stronger the spark strength.) Notes: 1.Please turn off the power before inserting the spark plug. 2.Connect the power supply, the red light is on. 3.After the green light is on, it belongs to the working mode. 4. DO NOT touch the spark plug by hand when working to avoid danger. 5.If you suspect a spark plug is not working properly, you can compare and test them to make an accurate assessment. Contents of delivery: 1 piece spark plug tester 1 pc power adapter