Locking fuel cap - chrome finish
Suits: DS, ID, 2CV / Dyane etc, H van, C35, Traction Avant (French models made after 1952)
Please note that if you fit a locking fuel cap to a D model saloon (which never originally had them), the extra height of the cap may mean that the flap on the wing contacts it before it's fully down.
Whether or not it does this depends on the adjustment of your wing and filler pipe. The majority of cars are fine, but some have to have the wing adjusted quite low in order to get panel gaps right, so may foul the locking cap.