Top quality, genuine piaggio mirror mount stem nuts. 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. These secure the mirror mount stems into the headset (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 the mirror stem.
 
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