MAGNETIC: The alarms work thanks to the magnetism between the alarm transmitter and the magnetic receiver. The 100 dB siren is triggered when an equipped door or window is opened (triggering distance: more than 10 mm). EASY: The alarm sensor and the magnetic receiver are equipped with an adhesive tape. No tools needed, just stick them on a door frame. TECHNICAL DETAILS: Transmitter dimensions: 9 x 3 x 2 cm; Magnetic receiver: 5 x 1 x 1.5 cm Batteries: 2x AAA 1.5V per alarm (not included) Volume: 90 dB NUMEROUS USES: Increase the security of your front door, terrace or balcony, your bedroom or that of your children - the set of 4 alarms and receivers gives you the choice. S > NOTE: Please make sure that your apartment or house has the right conditions for installing the security system without it being accidentally triggered. ANYWHERE IN YOUR HOME Secure your home thanks to the 4 alarms in different places: front door, balcony, garden, bedroom, window. EASY Installing the alarm