MAGNETIC: The alarms work thanks to the magnetism between the alarm transmitter and the magnet receiver. The 100 dB siren is triggered when an equipped door or window is opened (trigger spacing: more than 10 mm). EASY: The alarm sensor and the magnetic receiver are equipped with a adhesive tape. No tools needed, just stick them on a door frame. TECHNICAL DETAILS: Transmitter dimensions: 9 x 3 x 2 cm; magnet receiver: 5 x 1 x 1.5 cm | Batteries: 2x AAA 1.5V per alarm (Does not contain)| Volume: 90dB MANY USES: Increase the security of your front door, terrace or balcony, your bedroom or the children's room - the set of 4 alarms and receivers give you the choice. NOTE: Please make sure that your apartment or house has the right conditions for setting up the security system, without accidental triggering. ANYWHERE AT HOME Secure your home in different places with the set of 4 alarms: front door, balcony, garden, bedrooms, windows. EASY The installation of the alarm does not require any tools or cables. Just stick it to a window sill or door frame using the adhesive strips included with each part. Magnetic operation takes care of the rest. DISCREET Small alarms are convenient and discreet. Their white design does not degrade the aesthetics of your room. NOTE Make sure that your apartment or house has the right conditions for the installation of the security system, without accidental triggering (the distance transmitter - receiver must not exceed 10mm). TECHNICAL DATA Dimensions transmitter: 9 x 3 x 2 cm / receiver: 5 x 1 x 1, 5 cm Batteries: 2x AAA 1.5V per alarm (Does not contain) Volume: 90dB Maximum distance between transmitter and receiver: 10 mm