This kidde home protect smoke alarm uses optical sensor technology and is ideal for use in bedrooms 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 an additional voice alarm that clearly announces the detection of smoke it is simple and easy to install thanks to its single screw mounting bracket with a hush button feature that lets you silence nuisance alarms and a test button