The ballasts are 4 tube
ballast. I will have to mount them on top of my Walmart ShopLights. I have 3 of them hanging in a 2X4 shelfing unit. The other 2 I have behind the E&F unit in the Hydroroom. I plan to overdrive all of them.
Here is a picture with all 5 of them hanging. I have since covered the back of it with mylar, and have redone it some.