Choose a carbon monoxide alarm listed with a testing laboratory, meaning it has met specific standards for protection. Whether you select a unit that requires yearly changing of batteries or one you change at the end of the 10 years, either will provide you with protection.
CO alarms also have a battery backup. For the best protection, use combination smoke and carbon monoxide alarms that are interconnected throughout the home. These can be installed by a qualified electrician so that when one sounds, they all sound. This ensures you can hear the alarm no matter where you are in your home.