Top quality, genuine piaggio mirror mount stems or bracket holder rubber cover. The stems fit through the hole in the headset top and screw into the headset base bottom, the headset top should already have the holes cut into it to fit these rubber grommets, they form a tight seal and stop water egress into the headset.
Please note: you need to take the throttle or  gear rod out (depending on which side it is fitted to) to fit the mirror stems.
 
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