Product features: easy installation, stable and affordable. Small size Main part specifications: length 6.2cm width 3cm height 2cm Accessory specifications length 5.4cm width 1.3cm height 1.1cm Product Introduction: Using electromagnetic induction technology, installation is easy and inexpensive. In the open state, as long as the doors and windows are open, the machine will emit a 90db alarm sound. Staying away from anti-theft doors and windows bothers you. Fully enjoy sunshine and freedom Product use: Installed in homes, businesses, doors and windows, cabinets, computers, drawers, etc. ., where others are not allowed to open, when thieves open doors and windows or computer chassis; Or for business stay outside the hotel opens the door and it warns you to check immediately to make sure your belongings and safety are at risk. Product Usage: Just tear off the adhesive paper on the back of the security alarm lock and apply it separately to both sides of the door or window (leave a gap of 0-2 cm), when you use it, just dial the switch to "on" position, it is standby, if someone move or open the door, computer frame or window drawer , it immediately emits an audible alarm to deter thieves and remind you to watch until you dial the switch to the "OFF" position or close the door or window, The computer chassis, the drawers stop. Product power supply: this product uses 3 lr44 1.5v button batteries (already included in the device) Package contains: 2 sets of alarm!