Top quality, genuine piaggio mirror mount stems or bracket holders. These fit through the hole in the headset top and screw into the headset base bottom, the disc, Milennium and later PX models have the holes already cut out to take these. They are secured by a special nut (not supplied but available here)
Please note: you need to take the throttle or  gear rod out (depending on which side it is fitted to) to fit these.
 
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