The Siren Board

What is this thing next to the Sentry? Its inactive after the Sentry next to it was installed next to it. If you know what it is let me know. Thanks! https://maps.app.goo.gl/AVRrSq6e74cdemPh7?g_st=ic

This was covered thoroughly in a topic of the exact same name. Please search before you ask questions that are already answered.
viewtopic.php?t=27543