DESC: Onelink, Battery Operated Combination Smoke & CO Alarm, For Use With Onelink Interconnected Wireless Home Fire & Carbon Monoxide Safety System, Battery Operated Combination Photo Electric Smoke & Carbon Monoxide Alarm Connects To Any Onelink System, This Alarm Provides Both Alarms & Voice Alarms For Smoke & Carbon Monoxide Situations, Wireless Connects To Alarm When The Other Alarms In The Onelink System Go Off.