FSBT-5/8 CS/SS Ball Transfer Unit 5/8" Main Ball Proudly made in the USA FSBT-5/8 CS/SS Ball Transfer Unit, the main ball is 5/8" Inch, FSBT-5/8 CS/SS Can be recessed into the surface of the application forming a smooth and multi-directional rolling surface, Unit available with carbon steel balls or stainless steel balls to provide corrosion resistance.