This kidde home protect smoke alarm uses optical sensor technology and is ideal for use in hallways and landings powered by a sealed in 10 year lithium battery that lasts the full life of the alarm and never needs replacing when activated the alarm has a loud 85 decibel alert and a high intensity emergency safety light to help guide you to safety in the event of a fire in the home it is simple and easy to install thanks to its single screw mounting bracket with a hush button feature that lets yo