Ball is right size. 2 5/16 in. It's a Reese adapter for the gooseneck. I appreciate all the input referencing gooseneck versus 5th wheel. So darn confusing and a hundred people will have their 100 preferences. The reason I picked gooseneck is the vehicle was already set up for it and the sales and service people did not voice any negative points to a goose neck. Its always after the fact you start to find the negatives. Thanks to all! Anybody looking for a gooseneck adapter? I got one!