The First Alert 2-in-1 Smoke & Carbon Monoxide Alarms with Voice Alerts in a 2-pack are reliable and essential devices for any home. These alarms feature a photoelectric smoke sensor and an electrochemical carbon monoxide sensor, providing early detection of potential hazards. With a 10-year built-in battery, you can rest assured that your home is protected for an extended period of time. The voice alerts feature ensures that you are alerted in case of emergencies, making it a valuable investment for your safety and peace of mind.