Features: -Using advanced infrared detection technology, reliable performance; -Infrared sensor automatically detects human body signals and issues 'DING-DONG'; -Infrared sensor detection range: 110 °, 0-5M; -The induction doorbell is easy to install (1 set on the desktop or hang on the wall) and can be placed in doorways, windows, driveways. - Use 3*1.5V AA batteries ( Not Included). Specifications: Alarm type: Sound. Battery: 3 PCS AA batteries. Range: 0-5M . Direction: 110°. Material: ABS plastic. Color: White. Size: 10 x 6.3 x 3.5cm/3.9x2.5x1.4in. Range of use: 1. Doors, windows, homes, shops, businesses, etc. Installation and use method: 1. Push the battery cover on the back of the doorbell in the direction of the arrow, insert three AA batteries (alkaline batteries are recommended), and close the battery compartment cover. 2. Turn the doorbell switch to the voice file or Dingdong file. 3. When a guest enters, the doorbell will sound. Package Included: 1 x IR Sensor Alarm. 1 x Mounting brackets