Shimano dura ace di2 ad91 r9150 braze on adaptorthe dura ace di2 ad91 r9150 braze on adaptor from shimano allows the mounting of a r9150 di2 front derailleur to frames that have 34 9mm seat tubes and no braze on mount it is constructed from a lightweight alloy and provides excellent fit and rigidity to help shifting efficiency features 34 9mm clamp size allows braze on derailleurs to mount to non braze on framesa 2 year warranty is offered with all shimano products from chain reaction cycles