The ELAC "Jet" speaker line from Germany.
From their website:
The JET tweeter was delveloped to perfection on the basis of the famous 'Air Motion Transformer' by loudpseaker pioneer Dr Oskar Heil. Its principle: a concertinaed foil membrane is driven by a strong magnet system of neodymium rods.
This 'motor' drives the air considerably faster than the conventional pistonic technique. High sensitivity and extraordiary dynamics are the result.
Good luck in your search.
From their website:
The JET tweeter was delveloped to perfection on the basis of the famous 'Air Motion Transformer' by loudpseaker pioneer Dr Oskar Heil. Its principle: a concertinaed foil membrane is driven by a strong magnet system of neodymium rods.
This 'motor' drives the air considerably faster than the conventional pistonic technique. High sensitivity and extraordiary dynamics are the result.
Good luck in your search.