I have a 2016 X254. It has a king bed slide out that extends off the back or tail end of the trailer. It appears that there is a portable light that is supposed to plug into the ceiling, much like the portable lights found in a pop-up camper. I did not get one with the new purchase of my trailer.
I contacted the dealer and Jayco directly. Neither were much help. I can buy the one pictured for about $35 off Amazon that would plug into the socket I have for one. The problem is I don't have the tubular tent support found in a pop-up that it is designed to clamp it to. I have what you see in the picture. It's two smaller diameter U-shaped brackets (smaller than a tubular tent support) and I have no idea what portable type of light is supposed to clamp there.