Does only Rohloff manufacture the sprocket for their Speedhub 14? Are there any manufacturers other than Rohloff who make the sprocket for the Rohloff Speedhub 14?

Is the sprocket Rohloff specific or is it a standard / general / everyday part?
This is the email reply from Rohloff customer support


  It is always possible that parts are copied. To ensure warranty and reliability, we advise against buying copied parts. Especially because the  hardness of the metal of the sprocket is important.