Misfire Test. Convenient for intuitively understanding the operation of the ignition coil. Easy to read: Clearly visible white markings make it easy to read the measuring gap. Depending on the spark color and spark gap, the quality of the coil can be determined. Screw-on mounting for quick and easy adjustment of the spark gap. Prevents ignition coil from misfiring and burning out. Prevents ignition coil from misfiring and burning out. Alligator clips securely ground. Screw mounting for quick and easy spark gap adjustment. Convenient for intuitive understanding of ignition coil operation. Find dirty spark plugs, bad points, bad wires or connections, etc. Material: Metal Diameter: 22mm. Length: 115mm. Please allow 1-2cm differs due to manual measurement, thank you. There may be slight differences in the color tone of the pictures and the actual item. Package Includes: 1 x Spark Plug Tester