The Sennheiser HD 558 Over-the-Ear Headphones have an internal Surround Reflector that delivers an immersive audio experience. They are equipped with the E.A.R. technology so that the sound reaches the ears directly from the headphones. These headphones have Duofol diaphragms, which eliminate the unwanted resonances to render detailed sound quality. In addition, these headphones include comfortable velour ear pads and headband cushion that enables long-lasting usage. Further, they offer a frequency range of 15 Hz to 28000 Hz and an impedance of 50 ohms.