First Alert SCO501CN-3ST (Series SCO500) ONELINK Battery Operated Combination Smoke and Carbon Monoxide Alarm with Voice Location Color: White Model: SCO500 Tools & Home Improvement Wireless enabled battery operated combination smoke and carbon monoxide alarm Interconnects with other First Alert ONELINK enabled alarms to create a wireless safety network Exclusive voice alarm with up to eleven programmable locations to tell you where potential danger Photoelectric smoke sensing technology and Electrochemical carbon monoxide sensor Includes Test/Silence Button - Low Battery Warning - End of Life Timer and 7-year limited warranty