I bought mine on eBay but they appear to have removed their shop from eBay
MTS Racing was the supplier.
I have googled around and found this but my German language skills are rubbish so I can only assume this is the same part.
(Google translate says “ Technical data of the pressure pin: suitable for many clutch levers of Brembo axial pumps, 3-part (actual pressure pin, bolt and grub screw), the pin has a nose for actuating the clutch switch “ )
Hopefully someone will be along to translate and confirm