This conversion branded bearing is intended to allow an ETS crankshaft to be installed in a standard Vespa PK 50-125, PV, or V50 engine housing.
Especially unbalanced crankshafts with play or light flywheels can cause such high stress on the crankshaft that the crankshaft cone breaks during operation.
The ETS crankshaft has a larger diameter for the bearing and the shaft seal on the flywheel side, thus providing a significantly more stable shaft cone. However, the flywheel of the PK with a 20mm cone remains compatible.