"Chief’s CMA165 Junction Box Adapter makes finished or new construction home projector installations quick and easy.- With just a 4"" hole in the ceiling, you can install a projector by suspending it between ceiling joists- Includes junction box mounting brace and a 5"" round plate that adapts to 1.5"" NPT extension columns- Installation is similar to that for ceiling fans- The ceiling plate mates with a standard fan mounting junction box- Expands to fit 16"" or 24"" joist spacing"