The Puck offers in-room temperature control by simply rotating the Puck without having to use the Flair app. If you have a house guest or use your home/room as a short-term rental and don't want to give the guest access to your smart phone app, rotating the Puck is a good option.
Alternately, remote sensors offer occupancy tracking, and Flair can be set to use this information to set rooms to active or inactive.
See also: How Many Flair Pucks do I need?