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