In Danish, JERN means IRON, which refers to the cabinet material.
We use a special grade grey cast Iron (Vibrakill TM), with a very high amount of Graphite (Carbon) mixed in the Iron.
The Graphite dampens our cabinets vibrations 100 times better than Aluminium, and much better than MDF and wood.
Iron is also much stronger and heavier. This also reduce cabinet vibrations, so you only hear the good sound from the loudspeaker cones.