The Riser Cap is a very durable part molded using a long, 60% LGF Polymer.  It’s an abrasive material, but the c-core itself has shown extremely low levels of wear even after 10 years of production.  We’ve replaced other mold components due to wear but not this, and actually we just wanted the new c-core so that we could have the older one as a backup.  Also, the c-core helped eliminate a secondary machining operation that would have been necessary had we used unscrewing instead.  This part has both an inside diameter thread and an undercut at the bottom of the thread where a seal gets inserted.  What’s kind of unique with this part is that we’re also molding an external thread using an Ex-Cav, and this was a first for Roehr in terms of both the size of the c-core (6+” diameter x 2 1/2″ high) and creating both inside and outside diameter threads on one part.