Handlebar Expander Ring - Piaggio Zip - 563327

The handlebar expander cone is pulled into the steerer tube by tightening the handlebar expander bolt , causing it to expand and become wedged. This special ring is located at the top and prevents the bolt from entering the handlebar.

Always use original parts, but especially in this case. Because if your handlebars aren't properly secured, you'll be riding around like you've got a few too many.