Foldable, eye-catching black and silver, open-backed headphone that satisfies the highest of listening demands with new aluminum nameplates. Technologies: S-Logic™ Natural Surround Sound, MU Metal shielding (ULE-technology), Safer hearing. Distinguished by it's airy tone and its modern and elegant design, the HFI-2400s 40mm gold-plated driver provides the finest of three-dimensional sound thanks to Ultrasone’s patented S-Logic™ technology. The HFI-2400 comes outfitted with the MU Metal shielding, just like all other Ultrasone headphones, that reduces the amount of magnetic radiation emitted from standard headphones, up to 98%. Technical specifications: S-Logic™ Natural Surround Sound, Dynamic principle, Frequency range 10 Hz - 25 kHz, 75 Ohm impedance, sound pressure level 94 dB, MU Metal bufferboard, reduced field emissions in accordance with ULE (Ultra Low Emission) standard, 40 mm gold-plated driver, 292 g (without cord), detachable straight cord (length approx. 10 ft.) incl. 1/8" - 3/4" gold-plated adapter, transportation bag, demo CD, instruction manual, long-term availability of spare parts.