Universal bath and sink plug

Judging by how many of these we sell in the shop, everyone needs a univeral plug. It really does seem to fit any plug hole, from baths to the kind of kitchen sink with the  really big plug holes (see pictures of the second sink, dirty, but it's only coffee I can assure you. The main picture is a famous - and very clean sink belonging to @nikkiward and @georgeegg). 

It measures 7.5cm across, made from rubber with a generous chain.