Foldable, closed-back high quality headphones with very exclusive design and extraordinary sound, offering the highest standard of technologies: S-Logic� Natural Surround Sound Plus MU Metal shielding (ULE-technology) Safer hearing Technical specifications S-Logic� Natural Surround Sound Plus Dynamic principle Frequency range 15-25.000 Hz Impedance 75 Ohm Sound pressure level 99 dB MU Metal bufferboard, reduced field emissions in accordance with ULE (=Ultra Low Emission) standard Driver 40 mm gold-plated Weight 285 g (without cord) Straight cord, length ca 3 m 3,5/6,3 mm screwable gold-plated plug Transportation bag Demo CD Instruction manual Long-term availability of spare parts Character Eye-catching exclusive design and sand-grey coated. Experience the complete isolation of closed-back headphones and the honest sound of open ones. The high class gold-plated drivers of the HFI-680 are very sensitive and provide a maximum of transparency. ULE-technology To understand what ULE-technology does, you need to know that most headphone drivers produce low-frequency magnetic fields as they convert an electric signal into an acoustical signal you hear as music. In response, Ultrasone developed a special MU Metal shielding (ULE-technology) to reduce the radiation by up to 98% compared to current headphones. The ULE-technology has stood the test of international review and is recommended by technical surveillance organisations. S-Logic� Plus S-Logic� Plus is the enhanced version of the S-Logic� System. The specific acoustically designed earcups of the new HFI models and their stereo tonal fine tuning of the acoustic reinforcing devices present sophisticated sound and technology. Due to an additional damping, drivers and the bufferboard complement one another with the new spatial sounding unit. The final result is a most neutral sound impression including optimized distance perception of voices and instruments.