The Waterfall FLIP is a type of Unidirectional Gateway whose orientation can be physically reversed, enabling safe scheduled updates to OT networks without the vulnerabilities firewalls always introduce. The FLIP is deployed to routinely provide safe updates for the OT network such as operating system updates, updating antivirus signatures, uploading batch productions orders, and security updates.

Reversing the FLIP is possible by either physically pushing a button on the device, or by  physically connecting to the management port and scheduling reversals.