These black orings replace the metal clamps (CVA pin retainer) on the center drivelines of the RC8 that hold in the pin. Each order comes with 4 orings. With these orings you can remove the set screw holding the pin which will dramatically free up your drive train and also allow you to take apart your CVA quickly in order to relube for the most efficiency without screaming at the metal clamp trying to get it off.