Flipo 2-in-1 Personal and Door Alarm
This device can be placed on the inside door knob and will trigger a loud alarm as soon as a person attempts to open the door from the other side. It can also be carried in areas of potential danger such as being alone in the wilderness or traveling through unknown territories at night time.
The advantage of an alarm is that it will deter offenders as the the risk of getting caught is amplified by the attention that the 2-in-1 alarm can bring. In addition, it can give you early notice of potential danger when used as a door alarm. To use as a personal alarm, simply pull the string to trigger the alert system.
*Note: Will not work on metal doors