Is there a hitch adapter for a ball in the truck?

I have seen the Andersen Ultimate 5th Wheel Connection - Gooseneck to 5th Wheel Adapter. It looks like it works like a normal 5th wheel hitch would. I talked to a couple of people that have one and they say it is great.

It would have way less flex than the tube type adapter. It also leaves your bed flat for regular hauling. It is my next upgrade when I get the 5th wheel we are lookin at.