Each of the six balls rest in a separate grooves notched out of the shell on the end of the input shaft. These grooves guide the balls which are surrounded by a cage and then a star-shaped gear. This configuration all rests inside of a cup that is connected to a splined and threaded shaft.
Rzeppa joints are used in applications where even flexible shaft couplings would not have the misalignment capabilities needed. They can typically operate at angles up to 48° and sometimes even higher. The Rzeppa joint was initially designed for the automotive industry—this is still where they are most commonly found.