20mm aluminium rivet.

Reduce the length to 18mm to secure the cover washer on the Starter Clutch on Laverda 3 cylinder models with a Series 1 engine 1000 and 1200 models 1973-1980.

This is an aluminium alternative to the  steel rivet. It can be pressed cold

The use of a hydraulic press to install the rivet is highly recommended.