This works in conjunction with the ballast and usually two come with every light. You can couple up to three 50’ head extensions together with HMI’s but not anymore then that. Sometimes two is all you can get depending on the manufacturer. Many times when a light does not work, it is because of the head extension going bad in some way.
With fluorescent lights, Kino Flo has always been the leader. These lights are easy to use and easy to control. They’re so lightweight that I use them for almost everything.