The original Nest Protect combination smoke and carbon monoxide alarm aims to make that alarm in your house "less annoying." Consumer Reports tested it in February 2014.
Smoke detector and carbon monoxide detector that speaks up in a friendly voice to give you an early warning when there's smoke or CO in your home
Google Nest Protect - Smoke Alarm - Smoke Detector and Carbon Monoxide Detector - Battery Operated , White - S3000BWES
Cylon.js - Nest Protect Driver
Is Nest Protect Worth It?
Nest Protect Update Brings Pathlight Controls and Steam Check
Nest Protect Wired Integration - Devices & Integrations - SmartThings Community
Nest Protect Review
How Nest is creating the conscious home, one smart device at a time
DIY Google Nest Protect Wired Smart Smoke and Carbon Monoxide Detector
Nest Protect review - The Verge
Don't Forget To Test Your Smoke Alarms This Weekend
Google Nest Protect
Tested In-Depth: Nest Protect Smart Smoke Detector
Recommendations for Home Assistant smoke detectors