This is the plastic swivel half-ball as fitted to all original 2cv mirrors, made for Citroën by Geco. (This is an original Geco part).
We have found that it can also be used to help repair some other Geco, Cipa & Gemo mirrors as fitted to many other Citroëns, Peugeots, Renaults etc.
The other parts shown in the photos are not included. They are shown to better illustrate what the plastic half-ball is for. (We do have the special screw and sleeve-nut available elsewhere, if you need them).
We also have an alternative swivel kit, which is a cheaper option than the original parts.
(Navigate to mirror parts to see all these items and more).