Delegate unit: The conference unit allows the delegate to speak, request to speak and listen to speech. Each unit comes with headphone jack and volume control for delegates to listen to the floor speaker, and adjust volume level for comfortable listening. Built-in speaker automatically mutes when microphone is live. 1 to 4 delegate microphones can be active at the same time. Multiple chairman and vice-chairman units can be used in one system, and can be active at any time regardless of preset delegate mic limit. Delegate unit can be configured as vice-chairman unit via software. Chairman unit has the additional priority button to override all delegate units to control the conference.