Nest adds a $39 indoor temperature sensor to its line-up

Nest is launching a sensor that works in tandem with its Nest smart thermostat to read the temperature in separate rooms.

The sensor works with the Nest Learning Thermostat and the Nest Thermostat E to make sure a specific room stays as cool or warm as someone wants. They're meant for indoor use and can read temperatures from 32°F to 104°F.

Just 1.9 inches by .8 inches, the sensors are small — and can sit flat on a surface or be attached to a wall. It communicates via Bluetooth with the 3rd generation Nest Thermostat (sorry — not the 1st or 2nd generation) and must be placed within 50 feet of the device. You can link up to 18 sensors together, but only six per each smart thermostat.

The device is now on sale through the Nest web site, priced at $39 for each sensor, or $99 for a three-pack. They start shipping in April.

Check out The GearBrain, our smart home compatibility checker to see the other compatible products that works with Nest.