The app also lets you monitor what’s happening in your home and test alarms remotely, and it teaches you how to best use your smoke detector. This smoke alarm is only one piece of Nest’s larger home automation system. Not only can you network multiple Nest Protect units together, but you can also connect other Nest devices such as thermostats and security cameras. Additionally, the Nest Protect is compatible with other smart home networks including Nexia, Vera, Wink and Google Home; it doesn't work with Amazon Alexa or Apple HomeKit. Unfortunately, the two year warranty is shorter than those from First Alert and Kidde. Read the full reviewBest ValueKidde KN COSM B RF$49. 72 View at AmazonCheck Walmart?Detects both smoke and carbon monoxideDoesn’t require a hardwired connectionCan connect to multiple alarms via Wi FiPerformed poorly in our detection testsRequires extra equipment for the mobile appOnly compatible with Wink smart home platformThis alarm is two devices in one: a smoke detector and a carbon monoxide detector. It’s very easy to install because it runs on changeable batteries so you don’t have to hardwire it into your home’s electrical grid. If the Kidde KN COSM B RF detects an emergency in your home, it sets off a tone alarm as well as a voice alarm that gives instructions and tells you what the danger is. It also uses voice notifications to let you know when you need to change the battery. If you buy more than one of these detectors – and you should!– you can network them through your home’s Wi Fi network.