Slightly bigger than the Nest Protect, the First Alert Onelink Safe & Sound features a 10W BMR speaker which is extremely powerful. The LED status indicator flashes red during an alarm and serves as a nightlight. The built-in Bluetooth radio and Wi-Fi radio sit side-by-side the 85dB siren and can be connected to other smart home devices.

If the First Alert Onelink Safe & Sound detects smoke or carbon monoxide, it will send a notification to your phone. The notification will show a button for dialing 911 or a dismiss button to silence the alarm. You can also use Alexa and Siri voice commands as well as create smart home automations for added convenience.

Although installation isn't difficult, you do need to hardwire it to a junction box. If you're not familiar with this process, an electrician will need to be called out which isn't exactly convenient or inexpensive. However, once hooked up, you will end up with a smart carbon monoxide detector that's powerful, packs a lot of features, and will keep you safe.

The Google Nest Protect is an expensive investment but one that's worthwhile if you want to protect your home and family from potential life-threatening smoke and carbon monoxide. With a circular LED, this smart carbon monoxide detector can indicate whether there is smoke or CO2 in your home. Yellow means it's been detected but hasn't reached critical levels, while red indicates you should leave your home immediately due to a critical alert.

Setting up the Google Nest Protect is really simple; just screw it into the ceiling and connect it via the Nest app on your Android or iOS smartphone. Once connected, this alarm will not only let you know there's something wrong with a siren, but it will also alert you via your phone and offer detailed information. For example, it will tell you if smoke or carbon monoxide has been detected and in which room.

Running self-checks is another thing that this smart carbon monoxide detector does. It makes sure the Google Nest Protect is working at all times and triggers a siren once a month to be safe. You can also connect it to other smart home devices like Google Home, Philips Hue, and more.

The First Alert Z-Wave Smoke Detector & Carbon Monoxide Alarm is easy to set up, requiring just two AA batteries to work. To control the alarm, you can use a Z-Wave Plus controller, SmartThings, Nexia Home Intelligence, and Ring Alarm. To test it, you can press the single test button which will sound the loud 85dB alarm to ensure your home is protected.

Receive real-time notifications from your First Alert Z-Wave Smoke Detector & Carbon Monoxide Alarm when smoke or carbon monoxide is detected, straight to your phone, letting you act no matter where you are.

The Siterwell WiFi Smoke and CO detector require AA batteries to work. There's no hardwiring required, but once set up, you can connect the device to your home's Wi-Fi and access it via the app. And, if there are multiple people in your home, they can access it too.

The main benefit of being able to access this CO detector via the app is the real-time notifications. Whether you're at home or not, you'll receive alerts if the detector gets triggered by smoke or carbon monoxide. There's also a voice alert, so you're instantly aware of any issues if they arise.

However, getting the Siterwell WiFi Smoke and CO detector to pair with the app can be tricky. It's a little temperamental, and will only work with 2.4GHz Wi-Fi. But, once paired, you'll be able to appreciate this device's ability to check itself for faults, detect any potential dangers, and alert you to keep you safe.

The AEGISLINK Wi-Fi Smoke and Carbon Monoxide Detector make keeping your household safe easier than ever. With no hardwiring or expert installation required, you can get real-time monitoring and alerts in minutes.

The TuyaSmart app lets you control notifications, such as low battery notifications, letting you personalize your smart smoke and carbon monoxide detector how you see fit, while also letting you check carbon levels at a glance from your phone.

With continuous checks, the AEGISLINK Wi-Fi Smoke and Carbon Monoxide Detector monitors itself for faults and issues, keeping you safe in the knowledge that your device is constantly monitoring your home to keep you safe, and will let you know if something goes wrong.