Ultra light billet EN8 steel race flywheelfor diaphragm clutch NOT Verto with ring gear for pre-engaged starter. The latest refinement of the Ultra-light Mini flywheel is that it is now made symmetrically to reduce harmonics vibrations caused by earlier versions identified by their large 3 slots, rather than the current 6 smaller slots- yet it still weighs just over 3.66kg (8.07lbs). This is considerably lighter than a safely lightened standard iron flywheel, and also provides a much hardier clutch surface.