When you need to warn folks of danger in an emergency situation in an area where no power supply is available, the Mini Hand Crank Emergency Alarm Siren is a must-have. You will get maximum sound with a minimum of effort and because it is lightweight, it can be easily transported to remote locations. The aluminum siren will fold up to a small size for ease of use. It has a sound rating of 100dB and an output frequency of 500 Hz. Use it at schools, public buildings, camps, for mountain rescue and road work.