Certified SafeThe smoke detector has passed UL certification, product quality is guaranteed. The smoke alarm don't contain any radioactive material and won't cause harm to human's body Humanized DesignLoud>85dB makes everyone in the house can hear the alarm clearly when the smoke alarm is chirping. If low battery there will be a signal alarm, which informs you to change a new battery Test ButtonThe smoke detector is easy to test by pressing the button for more than 5 seconds. Don't test by open fire, it will damage the alarm or ignite combustible materials and cause structure fire Easy InstallationThe smoke detector is operated with 1 year 9V battery. There are adhesive magnetic pads in the box to help you install the alarm easily on ceiling or wall in seconds, without worrying about the size, mounting plate and rewiring