A Chair or Chairman unit refers to a special type of microphone (i.e. a separate model number from Delegate microphones) that has special privileges.
This microphone is not subject to the Active Mic Limit, and can activate its mic as long as the system active mic limit is not reached (see below for more information).
The Chair unit also has a “Priority” key next to its mic activation button, which, when pressed, can deactivate or mute all active microphones, depending on the configuration.
Finally, certain models of Chair microphones can be configured to have certain meeting functions such as the ability to start/stop votes or activate any microphone.