Ballraced joints respond much more readily to the slightest control movement of servos, mixer levers etc. Instead of the ball in the ball-link there is a 2 x 5 x 2.3 mm ballrace, secured with an M 2 socket-head cap screw.
These ball-links are designed to fit 2.5 mm diameter pushrods. Select appropriate retaining screws according to the requirements.