This extension main unit is designed to connect with the HCS-8600M and HCS-4800M series main units, ideal for large meetings. It features two SC single-mode fiber interfaces for long-distance data transmission and five conference unit output ports for additional connections. The HCS-8600MEA includes two extension in interfaces and one extension out interface for further expansion. When it's used with the main unit and a central control system, the central control of the whole system power can be realized.