The First Alert CO600 is a good detector and comes packed with excellent features. It is relatively cheaper compared to other models. It does not need any special mounting and is easily plugged into a wall power outlet. It comes with a 7-year warranty effective after the first alert. It is also fitted with test and mute buttons and will require replacement after seven years. It has no battery back-up and the power sockets have to be of correct height for effective operation.
The Kidde KN-COPP-3 comes with a battery backup. It has an extension cord that extends to 6-ft making it easy to mount. It comes with a self-diagnostic button that informs you whether or not it is functioning properly. It requires replacement after seven years and has a warranty of only five years.
These two models have excellent features and both function properly. In the event of a blackout a person using the Kidde KN-COPP-3 can carry on with their activities with no fear while the First Alert CO600 stops functioning and will therefore not detect any carbon monoxide present being emitted from other sources of light. Carbon monoxide is a silent killer and this means that one needs to have something that is functioning and can be relied upon all the time.
You should only use First Alert CO600 if your wall sockets are of the correct height and do not be tempted to plug in the Kidde KN-COPP-3 too close to the floor. The amount of time that Kidde KN-COPP-3 has been in the market makes it the most reliable and best choice between the two models.