High-quality product. For windows or doors. Ideal entry warning sign for houses, apartments, mobile homes, offices, hotel rooms, garages and more.Very powerful 95 dB alarm. When someone opens the door or window illegally (the relative position of the primary and secondary parts changes), the alarm can emit a loud alarm, warning the intruder to leave and alerting the owner.This magnetic sensor can detect the status of your door or window. It can prevent children from sneaking in and ensure the safety of children, homes, garages, mailboxes, and businesses.You can easily install and use it. Press the on/off switch to turn the power on/off, then insert 2 AAA batteries (no batteries included). Remove the adhesive pad on the back of the door alarm sensor, andStick the door handle alarm in the target location.Excellent environmental friendliness and stability. Package contents: 4 magnetic sensors, 4 magnetic sticks.