As an alternative to pepper spray, a whistle or some other device used for personal safety, a personal security alarm is a wireless device carried with you in a purse or pocket or hooked to a keychain. It is a self-activating alarm designed to deter personal attacks. Contained within the personal security alarm is a high-decibel siren. When activated, usually by pulling a cord or removing a pin, a high-pitched alarm sounds. Should you be caught up in a dangerous personal situation, having a personal security alarm on your person is a fast way to attract the attention of bystanders.
Personal security alarms are very small, usually no bigger than a car lock transponder. Built in a sturdy plastic case, many personal security alarms have a pull-out pin. When removed, the 100-decibel-plus alarm sounds and does not stop until the pin is replaced. Power is supplied via a 9-volt or long-life lithium battery, depending on the alarm.
Keep the personal security alarm in your pocket, in a purse or bag or attach it to your belt for quick activation. The downside is that the pin must be removed for the alarm to sound. In tense situations, panic may set in and prevent decisive action. However, having the alarm on your person is a better option than not, should you ever need it.