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