First Alert, 10 Year, 2 In 1, Photoelectric Smoke Detector, With Carbon Monoxide Alarm, Talking Alarm Speaks To Indicate The Type & Location Of Directed Threat, Slim Design, Maximum Protection, Blends In Easily With Decor, Patented Smoke Entry System Allows For A Direct Path To The Smoke Sensor, Helping To Minimize Nuisance Alarms That Often Come From Cooking Smoke Or Shower Steam, Uses Photoelectric Smoke Sensing Technology That Detects Smoke Particles Most Commonly Produced By Smoldering Fires & A Highly Accurate Electrochemical Sensor To Detect Carbon Monoxide Gas, Loud 85 Decibel Alarm Sounds If Hazard Is Detected, Single Test/Silence Button Mutes Unnecessary Alarms & Tests Function, Simple Twist Lock Mounting Bracket Makes It Quick & Easy To Install, Lasts A Full 10 Years.