Amazon.com: Polycom Expansion Microphone Kit for Poly Trio C60. Includes Two Expansion Microphones W (2200-86430-001) : Electronics
Expansion Microphones - Increase the audio coverage of your conference room by pairing the Expansion Microphone with your SoundStation conference phone. | Poly, formerly Plantronics & Polycom
Polycom Trio Expansion Microphones for Trio 8300, 8500 & 8800
Amazon.com: Poly Polycom Expansion Mic for RealPresence Debut (2200-69631-001) : Office Products
Poly Trio C Series Expansion Microphones - microphone - 2200-86430-001 - -