Keep your family safe from both fire and carbon monoxide poisoning with the First Alert ONELINK battery operated combination Smoke and Carbon Monoxide Alarm. ONELINK offers the same interconnected functionality as standard hardwired alarms without wires. The alarms communicate with each other and may provide an earlier warning of potential danger when people are in different locations in the home. The sooner you know, the sooner emergency responders can be notified, this may help reduce the potential loss of life and property damage. When compared to retrofitting an existing home, First Alert ONELINK costs much less than installing hardwired alarms in existing walls and/or ceilings. They are cost effective and easy to install. First Alert Exclusive voice alarm is programmable with up to eleven locations. Additional battery operated alarms may be added to create a wireless safety network. Photoelectric Smoke Sensing Technology reduces nuisance alarms and is environmentally friendlier. The Electrochemical Carbon Monoxide Sensor is the most accurate technology available.