The Nest Protect Smoke and Carbon Monoxide (CO) alarm quiets down when you wave – no more swinging towels or brooms and trying to shut down a loud alarm in your home. It sends a notification to your smart device when the alarm goes off and when the batteries run low. Instead of just chirping and howling at you, the Nest Protect speaks and thinks using a human voice. It gives you a friendly ‘Heads-Up’ before burning toast turns into an emergency, and tells you which room the smoke or CO is coming from. Do ‘Low-battery chirps’ ever rattle your dreams? The Nightly Promise feature shows you its sensors and batteries are working before you doze off.