1. Compact design: The small alarm is more compact than most door and window alarms. It is self - installable - just peel and stick. This alarm can be easily installed on any type of doors and windows, such as swing doors, rolling doors, sliding doors, etc. 2. Loud anti - theft alarm: In the continuous alarm mode, once triggered, the continuous alarm will have a great deterrent effect on thieves and intruders. In the doorbell mode, when your children or pets leave home, the loud sound will effectively and quickly issue a warning. 3. Four working modes: General alarm, continuous alarm, door - closing alarm, and doorbell mode. You can adjust the mode by simply sliding the side switch up and down, and each mode corresponds to a different sound. For more detailed information, please refer to the product pictures. 4. Ideal applications: It is not only suitable for all types of doors and windows but also for drawers, filing cabinets, safes, garages, campers, offices, warehouses, stores, etc. 5. Low - battery indicator: It is powered by 3 LR44 batteries. It has low battery consumption and a long standby time. When the battery is low, it will emit a "beep" sound every half an hour. 6. Principle explanation: This alarm will sound when the door or window is opened. The distance between the main unit and the magnetic strip during installation should be less than 1 cm. When the door or window is opened, the main unit and the magnetic strip will move together. Once the distance exceeds 1 cm, the alarm will sound. 7. Installation instructions: - Step 1: Stick the double - sided tape on the back of the alarm and the magnetic strip respectively, and then firmly stick them on both sides of the door or window joint. - Step 2: Ensure that the inverted V lines of the two parts are aligned, and the distance between them should be less than 1 cm. 8. Four working modes: - General alarm: The alarm sounds when the door is opened and stops when the door is closed. Setting method: Lift the switch up. The prompt sound is "beep beep". - Continuous alarm: The alarm sounds continuously when the door is closed. Setting method: Lift the switch up, down, and up again. The prompt sound is "beep...". - Door - closing alarm: It sounds "beep beep beep beep..." when the door is opened and stops after the door is opened. Setting method: Press the switch up, down, up, down, and up. The prompt sound is a fast ringing of "beep beep beep". - Doorbell: It sounds "ding - dong" when the door is opened. Setting method: Press the switch up, down, up, down, up, down, and up. The prompt sound is a fast ringing of "ding - dong". 9. Alarm size: 56 x 30 x 17 mm. Magnetic strip size: 35 x 10 x 10 mm. 10. Alarm power supply: 3 LR44 batteries (included). 11. What you will get: 2 sets of alarms.