Combination photoelectric smoke and carbon monoxide alarm with 10-year battery helps protect homes from fire and dangerous carbon monoxide levels by providing up to a decade of uninterrupted monitoring. Comes equipped with dual sensors for reliable detection of two potentially deadly threats. If a threat is detected， the unit alerts you using audible signals， including a loud 85-decibel siren and a programmable voice alarm that indicates the type of threat and its location. A built-in 10-year lithium-ion battery provides continuous power for the lifetime of the alarm.