The perfect headphones for an active listener who needs to move from the living room to boardroom to locker room without missing a beat. Combining the sound reproduction of the Koss Porta Pro with a unique design that allows over-the-head or behind-the-head wearing, the Sporta Pro won't interfere with hats or hairstyles - a prime portable headphone. With Mylar elements ensuring accurate sound reproduction and minimal mechanical distortion, Koss Sporta Pros are a lightweight headphones that also feature computer-optimized rare-earth magnet structures (neodymium, iron and boron), which deliver uncommon sound clarity no matter what volume you listen at - even with low-voltage DVD and MP3 players. The Sporta Pro's comfortable ear cushions allow you to stay in touch with your surroundings. At a mere two ounces, Sporta Pros feel practically weightless, even after hours of high fidelity listening. Collapse them down into a compact protective package and tuck them into your briefcase, gym bag, or backpack on your way back to the office. Specifications: Frequency range: 15-25,000 Hz, impedance: 60 Ohms, Sensitivity: 103dB SPL/1mW