Technical specification:

Main Features:

> Battery Operated
   Long-life lithium-ion battery sealed in the alarm to lengthen its lifetime to 10 years in standby condition.    
> Operating Light (LED)
   Flashes approximately every 53 seconds confirming unit is powered.
> Low Battery Warning
  Alarm beeps every 40 seconds when the battery needs replacing.
>Alarm Pause (Hush mode)
   Silence your smoke alarm by momentarily pressing the test button when non-emergency smoke (e.g. steam), causes nuisance alarms. The red light flashes every 10 seconds to remind you that the smoke alarm has been silenced. The alarm will automatically reset after 15 minutes.

>Sensitivity Test Button
  Test the sensitivity, circuitry, batteries, horn.
>Loud 85 Decibel Piezo Electric Alarm
  Automatically resets when hazardous condition has passed.
>Easy Installation
   Fixings supplied.