Stud Holder Stud Holder is a swiss quality Bergeon tool. This is a specialized platform with a spring loaded button. When this button is depressed a very small jaw at the center of the platform opens to accept your balance wheel stud. The balance wheel with hairspring is positioned on the platform by inserting the staff in one of a series of holes on the platform. This series of holes allows you to hold balance wheels of various diameters. This Stud Holder holds the balance wheel stud, so that the hairspring can be inserted into the stud with complete control.