The information below is the description given by B & W from their website. This peticluar companion hitch is used but barely let me know if you have any questions.
The B & W "Companion" Fifth wheel hitches are designed to easily be removed to allow you to still use your bed for hauling cargo. The companion Fifth wheel hitch use the B & W Turnoverball under bed mounting system (sold separately) giving you the option to switch between gooseneck and fifth wheel towing. No hitch rails required! Its fully articulating head allows side to side and front to back pivoting. With its 1inch thick jaws fitting the king pin perfectly and its polyurethane bushings between head and coupling base eliminates sloppy start and stops and provides a quiet and rattle free ride.