I have just bought a quantity of used home wine making kit, included
with which were two items which puzzle me and might be nothing to do
with wine making...

There are two of them, one red outer, one blue, both have the stylised
word 'FROSTY' printed on the coloured outer. Inside the coloured outer,
is a dense foam lining, with the same foam forming the circular base.
In that base is a small central hole, maybe to release air as
'something' is placed in it? Side joint is stitched, base is stitched
to side panel.

Size is about that of a straight sided flat based 1/3 pint drinking
glass. They are too small to fit the bottom of a 75cl wine bottle.