The TS-691L is a Chairman unit of the TOA conference system, TS-690 Series of which compact and lightweight design makes it easy to install and store. Placing the speech button in ON position allows a chairman to speak and disable the speaker to prevent feedback. If the speech button is placed in the OFF position, the microphone cannot be used but the speaker is turned on, allowing voices from delegate units (TS-692L) to be monitored. Pressing the priority key on the chairman unit allows chairman to take precedence over any delegate units. And the TS-691L Chairman Unit comes with a long microphone as a standard accessory.