Replacement rubber seal / washer for 008445 Franke / Lira basket strainer plug (supplied with many Franke kitchen sinks made before September 2008). It doesn't suit any other type of plug.
Before ordering check the picture carefully to make sure the washer is the same as yours. The washer has a fine sealing lip and it is this that has probably worn in yours.
These washers have the markings L.I.R.A Italy and No. 00252 S
We also have the seal for the newer (after 2008) plugs, they are not inter-changeable.