I was under the impression that Sonnax made almost all the aftermarket stuff. So it didn't matter who you got it from, it was probably a Sonnax piece. Don't know the difference between one piece and two piece (didn't even know they existed) billets. I do know the single billet Sonnax input I have was different from the stock piece. The taper on the stock shaft was non-existant on the billet one. This alone adds much more strength. I believe that is the MAIN benefit of going this route. The shaft is thicker in an area that is prone to breakage.