Sennheiser PC 21. Device connectivity: Wired, Cable length: 3 m. Headphone frequency: 40 - 18000 Hz, Impedance: 32 Ом, Headphone sensitivity: 109 dB. Microphone frequency: 80 - 15000 Hz, Microphone sensitivity: -39 dB, Microphone input impedance: 2000 Ом