The stylish and ergonomically designed chairman unit has all the necessary facilities to enable the user to chair a conference. It has excellent immunity to RF interference from mobile phones. Similar in appearance to HCS-4891D/50 Delegate Unit, the HCS-4891C/50 Chairman Unit includes a microphone priority button. When pressed, the priority button causes all currently active delegate microphones to be switched off temporarily or permanently, allowing the chairman to take control of the meeting. A 4.3" touch screen can display speaking list, conference service, operation menu, etc.