The Nest Protect 2nd Generation is a practical helper in your home. It is a smoke detector equipped with various sensors. It not only alerts you with a light ring and sound when there is smoke, but it also detects carbon monoxide in the air, which is invisible and odorless to humans. When you turn off the lights, the night mode activates, indicating with a green LED ring that the Nest Protect is functioning properly. You can also use the nightlight feature, which turns on when you walk past the device, so you don’t have to navigate your home in complete darkness. If an alarm is triggered, you will receive an acoustic warning as well as a notification on your smartphone.