Kidde has been making residential safety alarms for decades. This plug-in carbon monoxide detector does exactly what you need it to do, with one key advantage: it keeps working when the power goes out. The included 9-volt battery backup means you’re covered during blackouts, which is when CO risks from generators or gas appliances often spike.

The electrochemical sensor is the same type used in professional-grade detectors. It measures CO concentrations continuously and triggers an 85-decibel alarm when levels become dangerous. The digital display shows the current CO reading in parts per million, so you can see if levels are rising before the alarm sounds. Setup takes about ten seconds—plug it into any standard wall outlet, pull the battery tab, and you’re done.

One honest limitation: the unit is slightly bulky and may block the second outlet on a duplex receptacle. It also lacks smart home connectivity, so you won’t get phone alerts. But for straightforward, reliable CO detection with power-fail protection, this is a solid choice.