LPBT-1 SS Flanged Mounted Ball Transfer Unit 1" Main Ball Proudly made in the USA LPBT-1 SS Flanged Mounted Ball Transfer Unit, Main Ball is 1" Inch, LPBT-1 SS is designed to be recessed into the surface of the application in a 1-3/4" hole, 1" Main ball rotates on (80) 1/8" support balls.