Flair Smart Vents use a light bar to help identify the unit. Each Smart Vent will display a unique light pattern when it is discovered during Setup.
The light bar is only active during Setup mode. Activate Setup mode in the Flair app by tapping menu | Home Settings | Flair Devices | toggle "Setup Mode is off". Match the Vent's pattern with those shown in the app to get the Vent's four-character ID. When you are finished, toggle "Setup Mode is on". After exiting Setup mode, the light bar will turn off.
This is an example shows how Flair displays the Smart Vent light pattern during Setup mode.