Expansion Microphones for Trio 8300, 8500 & 8800 Expansion Microphones Add greater microphone pick-up to cover larger spaces. Product Information Audio Clarity Clear audio no matter where you are sitting. Simple to Use Mute button and indicator so that everyone at the table has access without having to stand and walk across the room. Sleek Product Designed to bring performance without adding clutter. Conference phone sold separately. Set-up Single cable to each microphone for simple installation. Includes two expansion microphones. Poly Innovation Poly creates premium audio and video products so you can have your best meeting -- anywhere, anytime, every time. Our headsets, video and audio-conferencing products, desk phones, analytics software and services are beautifully designed and engineered to connect people with incredible clarity. They're pro-grade, easy to use and work seamlessly with all the best video and audio conferencing services. With Poly (Plantronics, Inc. – formerly Plantronics and Polycom), you'll do more than just show up, you'll stand out.