5/8 Stud Type transfer NSMBT-5/8 CS 1/4" Threaded Stem BearingNSMBT 5 8 CS Stud Mounted Ball Transfer Unit 5 8" Main Ball 1 4" 20 Threaded Stem Proudly made in the USA NSMBT 5 8 CS Stud Mounted Ball Transfer Unit, Main Ball is 5 8" Inch, 5 8" Main ball rotates on 3 32" support balls, NSMBT 5 8 CS stud mounted ball transfer is a heavy duty ball transfer unit, capable of supporting as many as 33 pounds (per unit). NSMBT 5 8 CS features a 5 8" inch ball bearing resting on 3 32 inch individual support bearings,