Need to identify fifth wheel hitch

BIL bought a 2015 GMC Sierra 3500 HD Denali dually and it came with rails for a fifth wheel hitch but not the companion. Looking to identify the proper hitch for the rails that are currently in the truck. See pic attached.

Also, can someone please provide an education on the "best" fifth wheel hitch available?

I know that in my case I own a travel trailer and I went with a ProPride hitch, said to be one of the safest and well designed hitch on the market. Is there a similar fifth wheel hitch? By similar I don't mean by design....I mean most innovative or safest.

http://i1079.photobucket.com/albums/w507/sscheitel/IMG_2367_zpsq4zuyvxs.jpg.html