First Alert PC910V  10-Year 2 in 1 Photoelectric Carbon Monoxide Alarm and Smoke Detector with Voice Alert, White Sleek, low-profile combination smoke and CO alarm detects two potentially deadly threats Programmable talking alarm speaks to indicate the type and location of detected threat Photoelectric smoke sensor detects smoke from smoldering fires while minimizing false alarms Electrochemical CO sensor alerts you to carbon monoxide danger from multiple sources Built-in 10-year battery offers continuous power for the life of the alarm