The Nest Temperature Sensor has been on pre-order since it was announced back in March this year and now it has finally started shipping. It's available with for $39. You can order the accessory from both Google Store as well as Nest's official website, although it's currently showing as out of stock at the former. You can place these sensors in your rooms so that your Nest thermostat is aware which room should be a certain temperature at a certain time of day. Keep in mind that the device is only compatible with the Nest Thermostat E or the 3rd gen Nest Learning Thermostat....
Source: https://www.gsmarena.com/nest_temperature_sensor_goes_on_sale_for_39-news-30830.php
