The model 903E Electret handheld microphone is designed for use in high-noise environments where speech intelligibility is desired, such as in aircraft cockpits, passenger cabins, control towers, or terminal areas. The electret element virtually eliminates EMI, RFI and magnetic signals channeling the full power of your communications system into crisp, articulate voice transmission with the RTCA frequency response. The microphone is recommended for advanced technology air transports employing electronic flight instrumentation systems (glass cockpits). Its proven electret technology will not decay or deteriorate in any way over extended periods.