The Polycom RealPresence Trio Expansion Microphone (P/N 2201-69085-001) is a high-quality microphone designed specifically for use with telecommunication systems and conference equipment. This microphone, made by the renowned brand Polycom, allows for clear and effective communication during meetings or conferences. The expansion microphone helps to enhance the audio quality and ensures a smooth communication experience for all participants involved. Ideal for professional settings, this microphone is a valuable addition to any office environment. 1 expansion mic near mint barely used. See pics for wear.