SITERWELL Smoke Detector, 10-Year Smoke Alarm with Photoelectric Sensor and Low Battery Warning, Fire Alarm with Built-in Battery and Fault Warning for Bedroom and House, UL Listed, GS526A, 1 Pack

Activation Before Installation: Press and hold the test button for more than 3 seconds until THE LED LIGHT IS ON, RELEASE IT within 2 seconds, and the smoke detector will make a “beep”, indicating that the activation is successful. Please do not long press the test button and wait for the beep, because It is not successfully activated method.
10 Years Life Time: The smoke alarm can be 10 years life time and has 10 years life time non-repalced battery. You won’t worry about replacing the battery any more. And it can save energy and protect environment.
Fault Signal Alarm: The photoelectric smoke alarm is very easily tested only by pressed the button more than 5 seconds, the low battery will have a signal alarm which will recall you to change a new battery.