Bosch O-Ring seal. Fits the Bosch BDU3XX electric bike systems.
For mounting the chainring.
Lockring 1.270.016.489 also required.
User’s Manuals for Bosch Electric Bike Motor Systems
Bosch Performance Line User’s Manual
Bosch Performance Line Speed User’s Manual
Bosch Active Line BDU2XX User’s Manual
Bosch Active Line BDU3XX User’s Manual
Bosch Active Line Plus User’s Manual