Beyerdynamic DT 108 Single Sided Intercom Headset 50 ohm Gray. Designed for broadcasting, film, TV, two-way communications and IFB intercom applications. A built-in noise canceling dynamic mic is attached to the single-muff headset. Headphone impedance available in 50 or 400ohms. Available in dual headset model DT 109. Headphone response 30Hz-20kHz Microphone response 40Hz-12kHz