The tweeters are titanium dome with ferrofluid cooling and a neodymium magnet structure. (ecoustics.com)
Other products, such as the Ferrolic by Zelf Koelman, have held ferrofluid displays. (inc.com)
Lewitt uses a material called Ferrofluid, which is a liquid with magnetic properties that is used to make hard drives and music speakers. (whitney.org)