Features: Comes with two test holes, you can test two spark plugs. Design f testing spark plug perfmance ignition resistance. Apply to 12V petrol vehicles. Plug play, convenient easy to use Durable reliable. Specifications: Power Supply: Input 100-240V AC; Output 12V 1.5A DC Main unit weight: 190G (without AC adapter) Dimension: about 1458560mm Detection pt: 2 pieces How to use: 1. Insert the spark plug into test hole 1 2. (Note: If you want to compare the new old spark plug, put the new spark plug in hole 1 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 indicat light will be charged. At this time, the indicat 3 lights up the tester is now wking at 1000 rpm. 4. Turn the key switch 4 clockwise again 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 befe 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 wking mode. 4. DO NOT touch the spark plug by h when wking to avoid danger. 5.If you suspect a spark plug is not wking properly, you can compare test them to make an accurate assessment. Contents of delivery: 1 piece spark plug tester 1 pc power adapter