spontaneous unaffected120db Wireless Touch Sensor Loud Door Knob Entry Anti Theft Alarm Alert Security 120 db supper loud alarm ringing. This alarm installed in your house, office, factory, when the doors and windows are opened by children or the theft, it will alarm you to check for safety. To stay at the hotel, you can install this alarm on the door and window, it will protect you, upon checking out, take the alarm with you for next-time use. Requires no special wire. Just hang on the inside door knob, open the switch, the piercing alarm will scare off any unwanted intruders, leaving you and your home well protected. When needed to use the alarm, only put the switch to "ON" position, and the alarm devices in stand-by. When the door or window is touched, it will immediately makes sound for alarm. And the sound will not stop until the switch is put to "OFF" position. Powered DC a 9V Alkaline battery(NOT Included).