Associated clutch nut (Pilot Shaft) and clutch nut clip for the RC10GT are constructed of machined steel. For Newer .12 OS Max engines. Has hex base for tighteningWorks on all .12 size motors (except on O.S. CZ-R's made before October, 1993. This item is installed to keep the flywheel in place, and the clutch bell rides on this. It also has a groove that the e-clip fits into, and this retains the clutch bell.