Entry chime mode: magnetic sensorIdeal for home, office or shop to announce the visitor's entryIt gives " Ding Dong" sound instantly when opening doorOperated by 3 x 1.5V LR44 button cells (included)Entry alarm mode: magnetic sensorThe twins guard detects entry protecting your shop, office, home or any entries inside a house requiring protectionEasily mounted on door frame by adhesive tapeIt gives an alarm sound instantly when opening doors or windowsMagnetic sensor detects entryBuilt-in high output sirenProduct size: 70 x 25 x 22mmMagnetic bar size: 40 x 15 x 14mm