This may help prolong our coil connections when they are constantly being yanked off the plug. The factory method of joining the plug wire to the plug terminal ( under the boot ) is cheap and good for the garden engs. it's designed for. But they were meant to come off the plug maybe three or four times ( to change plugs ) over their life span. We yank these wires off the plugs hundreds of times. There is also a boot on the coil tower of the RCMK coils, that is perfect for zipping as well.