Used to replace a T8 aquarium light ballast that is no longer working properly. A little upgrade with a small saw and some velcro and it's as good as new and even easier to replace next time. I'm sure it's of higher quality too. This version was about 4 times longer and heavier than the one that originally came with my light kit. Also, I paid about 40% less at Revain than I would at a large retail store and knew what I was buying.