Sennheiser HMD 46-3-6 - conference headset (air traffic control), dynamic headphones with ActiveGard. open ear-covering, 300 Ohms impedance, 98dB SPL, headphone frequency response: 20Hz-14kHz, dynamic capsule, microphone frequency response: 100Hz-12kHz. Weight: 150g. Includes 180cm cable (to open end).