Denon AHD2000 High Performance Over-Ear Headphones (Discontinued by Manufacturer) Over ear headphone metal hybrid compound molded housing Micro Fiber Diaphram acoustic optimizer Acoustic Optimizer technology improves dynamic bass by adjusting sound pressure balance on both sides of the diaphragm Reference-quality 5-45,000Hz frequency response 50mm Neodymium driver, Impedence - 25 Ohms