[Engine] Rocker cover gasket

[addo]

There are two gaskets, inferieur and superior. Citroën only cater for the top one as a separate part; you need to buy an engine gasket set to get the both or a lower item. Nice work, if you can get it.

As per the pictures (hey, the internet is trustworthy, right?) your Febi one is the lower or inferior unit whilst the Rienze item is the topmost one.