WW2 British RAF / spy contra plug

This is a WW2 item I never encountered before.
It is a perfect mint contra plug that was used for plugs of the C-type flying cap and some spy radio’s.
Don’t know what to tell more about it and picture will tell all.
In the picture you can see that it is packed in a box.
These are all sold.

Only have 1 left, with out box.

Markings: some detail markings on the plug
Condition: mint / unused