Order EPDM O-rings.
31.34mm X 3.53mm for the lower one.
31.42mm X 2.62mm for the upper one.
![Very Happy :-D](./images/smilies/icon_biggrin.gif)
Seems to work ok.
Hope that it works for all MILLE owners.
The piston diameter is 30.97mm.
I've now measured the clutch cylinder.
The lower groove is 37.0mm outer diameter.
The upper groove is 35.55mm outer diameter.
The lower groove is 11.3 mm down (the upper side of the groove)
The upper groove is 3.3 mm down (the upper side of the groove)