Cyber Acoustics AC-644 Behind the Neck Stereo Headset AC-644 with Boom Microphone + Free Labtec Verse 303 Desktop Omni Directional Microphone Stereo headset: Flexible mic arm, In-line mute and volume control; Sensitivity: -67dBV/microbar, -47dBV/Pascal +/- 4dB Connector: 2 standard 3.5mm audio jacks (audio in and out). Desctop Microphone System frequency response: 100Hz-10kHz; Input sensitivity: -56dV/ubar, -36dBV/Pascal +/-4dB.