[GreenKeys] Black tape

[GDM]

You are missing the most obvious answer.  Since few have any knowledge 
of "black" tape it must be super secret.  And if its super secret, it 
must have been used by the CIA to send their most secret messages.   
With that kind of "solid history" it should be sold on ebay for hundreds 
of dollars per foot.

You've found a black gold mine.

W9OAK