Spark Plug Tester Automotive Ignition System In-line Coil Tester Auto Test Tool Feature: 1)Quickly diagnose ignition system problems, lack or no spark condition. 2)Easily test ignition circuit continuity at each cylinder. 3) The tool connects between the spark plug and the plug wire. 4) Great for trouble shooting all internal combustion engines 5)Find dirty spark plugs, defective points, bad cables or connections, etc. Usage Method: 1) With engine off, remove spark plug wire. 2) Attach black connector spark plug. 3) Insert metal end of tester into spark plug wire. 4) Try to start the engine. 5) If ignition circuit is complete, bulb will flash Material:Plastic+Metal Main Color: As the picture shows Size Approx:Total length 29cm, test pen length 12.5cm, diameter 2.5cm, spark plug length 6.5cm Conversion: 1inch=2.54cm, 1cm=0.393inches Quantity:1Pc Package Content: 1X Automotive Spark Plug Test Tool