First Alert Smoke Detector and Carbon Monoxide Detector Alarm with Built-In 10-Year Battery, BRK PRC710 Keep your family safe with this battery-operated smoke and carbon monoxide alarm; built-in 10-year battery means continuous power for the life of the alarm Features electrochemical Carbon Monoxide sensing technology and photoelectric smoke sensor optimized to detect larger smoke particles produced by smoldering fires; helps minimize the number of false alarms A loud 85-decibel alarm sounds when Carbon Monoxide, and Smoke levels begin to rise Features a sleek, low-profile design to blend more fully into the wall and out of sight 10-year limited warranty; equipped with end-of-life signal chirp, so you know when it's time to replace the unit for your safety Rigorously tested to meet UL standards