The cylinder line is an integral part of the traditional ignition system and is the medium through which the ignition coil transfers energy to the spark plug. The cylinder line is roughly divided into four parts. The first is conductive material, the second is insulating rubber, the third is the ignition coil joint, and the fourth is the spark plug joint (there are some cylinder lines wrapped with a layer of insulating material to prevent the cylinder line from being burned out).
The number of cylinder lines is the same as the number of engine cylinders. With the development of science and technology, many cars now have no cylinder lines. The cylinder lines and the ignition coils are combined. One ignition coil per cylinder is greatly reduced in volume, which provides more convenient conditions for independent ignition of each cylinder.