This is a button set for the F-21 attachment, very similar to the one posted by Bill Parkinson. The enclosed packing list calls the buttons "Washers".
There are two "shutter" buttons and a number or regular buttons to complete the spy coat.
It would be interesting to know about the people working with these materials - making buttons, installing them, sewing them, picking the right coats, right people for the job, keeping it all secret.
This set is quite new, made in 1991. I purchased it from a
Uploaded on 5/6/2008 12:10:25 PM by fedka