Philips SHP9500 and its open-back, over-ear design is comfortable for long-term wear and has low impedance so that it will work great with and without headphone amplifiers, allowing you to enjoy greater sound transparency and smooth high frequencies. It comes with a 1.5m cable (removable) for freedom of movement for indoor use, as well as a gold-plated 3.5-6.3mm adapter for those with audiophile grade equipment. Frequency range: 12 - 35,000 Hz Sensitivity: 101 dB Maximum power input: 200 mW Impedance: 32 Ohm Acoustic system: Open Magnet type: Neodymium Speaker diameter: 50 mm