Dual Functionality: The 10 year battery operated combines smoke and carbon monoxide detection capabilities, providing comprehensive home safety protection against these 2 common hazards. With one device offering dual functionality, it enhances home safety while reducing the need to install multiple alarms. Accurate Alarming: The smoke and carbon monoxide detector uses photoelectric smoke sensing technology and has undergone rigorous testing and certification to meet UL 217 and UL 2034 standards, ensuring high accuracy and reliability. It promptly issues warnings, protecting you from the threats of fire and carbon monoxide. Do Not Disturb Mode: When the smoke alarm and carbon monoxide detector detects low battery or a fault, simply pressing the button will put the alarm into Do Not Disturb mode for approximately 10-hours, preventing nighttime alarms and frequent flashing, ensuring your sleep is not disturbed. Self-Check Function: The smoke detector carbon monoxide detector combo automatically checks every 80-seconds to ensure all sensors, alarms and battery functions are operating correctly, preventing issues from being overlooked or forgotten. If a problem is detected, the alarm will alert you to perform maintenance or replace the device, ensuring it remains in optimal working condition. Unique Voice Speaker: Unique smoke detector and CO detector alarms distinguish between smoke alarms and CO warnings. Co alarm: Warning, carbon monoxide, evacuate. Smoke alarm: Fire.