Guessing is good and here are the pictures of Stradivari tweeter:
http://www.audiostereo.pl/zalaczniki/1704187_2.jpg
and Guarneri Memento tweeter:
http://www.audiostereo.pl/zalaczniki/1704187_1.jpg
You can easily see how different is the tweeter from standard ring radiator. Front bafle is diferently shaped, magnet is double sized and there is acustical wood chamber.
http://www.audiostereo.pl/zalaczniki/1704187_2.jpg
and Guarneri Memento tweeter:
http://www.audiostereo.pl/zalaczniki/1704187_1.jpg
You can easily see how different is the tweeter from standard ring radiator. Front bafle is diferently shaped, magnet is double sized and there is acustical wood chamber.