Ultrasone Edition 8 Ruthenium S-Logic Surround Sound Professional Closed-back Headphones with Leather Transport Bag S-Logic Plus technology Dynamic principle, closed Frequency range 8 - 42000 Hz Impedance 32 Ohm Sound pressure level 98 dB S-Logic&#8482; Plus Natural Surround Sound Safer hearing Portable, closed headphone Frequency range 6-42,000 Hz Impedance 30 Ohm