First Alert is the category leader in fire safety and delivers reliable life safety products that help our consumers protect what matters most through innovation and performance. Carbon monoxide (CO) is the leading cause of accidental poisoning deaths in America, yet many people don't know they are suffering from CO poisoning until it???s too late. Symptoms of carbon monoxide poisoning are like the flu and you might not even know you're in danger. The CO250B alarm detects the CO you can't see, smell or taste in the air. It also features a Test/Silence button to check if the alarm is functioning properly as well as silence unwanted or nuisance alarms. This First Alert CO250B Carbon Monoxide Alarm is an essential product in protecting your home and family.