Hang the Vibration Door Alarm/Chime on a door knob. Turn the unit on to alarm. It will sound for 5-15 seconds, then shut off. The unit is now armed. The alarm will be activated when the door knob is touched or jarred, alarm will sound for 5-15 seconds (this is adjustable). Low battery indicator. Uses 9-volt battery (not included). Also acts as door chime. Off/Alarm/Chime switch.