Mionix Keid 20. Device connectivity: Wired, Device interface: 3.5 mm, Cable length: 3 m. Ear coupling: circumaural, Headphone frequency: 20 - 20000 Hz, Impedance: 32 Ом. Microphone frequency: 300 - 3300 Hz, Microphone sensitivity: -36 dB, Microphone connectivity: 3.5 mm. Volume control: Rotary