The Personal Alarm provides security against harassment or attack by emitting a loud high frequency sound that can be heard up to 250 feet. Ideal for both younger and elderly people, joggers, and anyone looking for a safety device that can be carried anywhere with ease. Since the alarms are on a key chain, they can be placed in your pocket or jacket where they stay within close reach when you need them. Deactivate alarm by pushing the pin back to its original position. Powered by the included three 1.5 volt batteries (LR44).