More Information Here: https://www.ecobee.com/ecobee4/
Ecobee 4 Smart Thermostat
Most thermostats only read the temperature in one place (usually the hallway) which can make other rooms uncomfortable. ecobee4 comes with a room sensor to help manage hot or cold spots.
When you place sensors in your favorite rooms, ecobee4 can read the temperature and detect occupancy. That's how it ensures comfort in the rooms that matter.