Activate before Installation Pull out the battery tab toactivate your smoke alarm. The GS525A smoke alarm must be activated prior toinstallation. Failure to properly install andactivate this alarm will prevent properoperation of this alarm and will prevent itsresponse to fire hazards. 10 Years BatteryThe smoke alarm has a builtin 3V lithium battery, which runs for 10 years and reminds you when the battery is low. When the alarm sends a fault signal, you must replace the product immediately UL2179th ListedThe GS525A is a photoelectric smoke alarm. Meets the testing requirements of UL2179th.The photoelectric technology, it is more sensitive in detecting slow smoldering fires which generate light smoke, little heat and may smolder for hours before bursting into flames TestMute ButtonThe smoke alarm is designed to test the normal operation of the product by pressing the test button. Weekly testing is required. The product is designed to be silent and not disturb your rest Magnet and Screw IncludedMagnets and screws are included, it can be easily mounted on the wall or ceiling. you can choose any installation method you need.