Not sure if CZ Custom makes their own, I know they sell factory ones that are ISPC Production legal (important to like, only me on here), however I believe Cajun makes his own as well as selling factory ones.
The one in my new new match gun is actually not a Pre B, in that the hook is the same as the regular post B ones, but it's reset is the same as the Pre B in my backup gun, I don't have the tools to measure them properly to compare how they are made.