A Puck measures environmental conditions, controls temperature and other settings in a room, determines occupancy, and communicates with air conditioning and heating devices.
The Flair Puck communicates with the Flair cloud, your Smart Thermostat, your Flair Smart Vents, and/or your mini-splits, window ACs, or portable heaters.
When a Puck is plugged in, it's called a Gateway Puck. When a Puck is running on batteries, it's called a Sensor Puck.
You will always need at least one Puck when using Flair.