Quickly diagnose problems with all ignition ,Connect the tool between the plug and the plug wire Normal of fire gauges as"purple blue and 2cm straight ,"if the ignition coil is bad when the color is red or Use this ignition tester to check the condition of the ignition system at each cylinder without going to expensive mechanics.The tester connects between the plug and plug wire in seconds to troubleshoot dirty plug connections,defective points and bad cables or connections.Connects in seconds. Colour:Black material:plastic Size:Jumping distance is about 0.8-1.5cm Package Contents: 1pcs * plug tester Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.