This is 4.3mm the titanium ball studs with ball end caps from Rhino Racing.
This kit can be used on most of the RC drift chassis.
Included:
20x Medium titanium 4.3mm ball stud
4x 90 degrees ball end cap
4x 45 degrees ball end cap
4x Straight angled ball end cap long
4x Straight ball end cap short
4x Straight ball end cap medium
4x Straight ball end cap long
2x Straight ball end cap super long