Topic: Large, fancy CWS bottle stopper

[Ivo]

Missed those but they seem to be for holding a rubber casket in place.

[Anne]

Gasket (rubber ring or grommet) perhaps, Ivo, not casket (box or coffin) ? 

[Ivo]

miracles exist :-)

[Chris Harrison]

He we go, folks.  There are four of these little nubs.  They are crescent-shaped and protrude by approx 1mm

I found a pair of calipers and measured the taper.  Ivo is quite right (as usual!).  The open end is approx 0.5 mm smaller - not visible to the naked eye, but definitely smaller.