The Audio2000'S ACC6540H-01 is a miniature condenser headset microphone featuring a micro-miniature construction for unobtrusive vocal pick-up. Furthermore, a high quality back-electret condenser microphone element provides the ACC6540H-01 condenser microphone with excellent sensitivity and extremely wide frequency responses. Polar Pattern: Cardioid. Sensitivity: -39 ± 3 dB (- 1,000 Hz). Output Impedance:< 680 Ohms. Frequency Response: 50 - 12,000 Hz. Power Supply: DC 1.5V (External Power). Connector: 3-Pin Mini XLR.