Magnetism: The alarm works thanks to the magnetism between the alarm transmitter and the magnetic receiver. The 120 dB siren will be triggered when the equipped door or window is opened (trigger distance: greater than 10 mm). Simple: The alarm sensor and the magnetic receiver are supplied with adhesive tape. No tools are required, just stick them on the door frame. Technical details: Transmitter dimensions: 9 x 3 x 1.8 cm; Magnetic receiver: 5 x 1 x 1.4 cm Batteries: 2 AAA 1.5V per alarm (batteries not included) MULTIPLE USES: Increase security at your front door, on your terrace or balcony, in your bedroom or in your children's room - this set of 4 alarms and receivers gives you the choice. Note: Make sure your apartment or house has the ideal conditions to set up a security system without accidentally triggering it. Note: The data are all measured manually, please allow an error of 1-3 cm due to differences in light and display, there may be color differences, please refer to
