Hand operated alarm is an audible warning device in order to indicate a dangerous or emergency situation  and designed to provide effective warning in applications where there is no power supply ,such as:Civil defence. Camp sites. Mountain rescue. Frontier sentry and coast guard warning.

Due to lightweight  thesirens can be easily transported to remote locations and folded up to a small size for easy of carrying,furthermore the price is quite cheap,so this kind of alarms are welcomed by customer