Vespa / Piaggio Self-locking Nut - M10 - Sprint / Primavera - 1C005302

You’ll find this nut in the subframe, also known as the swingarm or engine mount.

It is therefore subjected to considerable forces, and it must not work loose due to vibration.

So even though this nut is on the expensive side:

Always use this original locknut, so you can be sure it is securely fastened!