The hand crank alarm does not require a power supply and can provide an effective alarm in places where there is no power supply.
The desired alarm effect is achieved by simply manually shaking the handle clockwise at a primary speed (2500 revolutions per minute), producing a majestic sound with a large shock and long wavelength.
When power and traffic are blocked, other mobile alarms cannot enter the alarm area, and the portable and practical hand crank alarm becomes a very practical alarm.
Widely used in factories, schools, open-air military camps, mountain rescue and anti-ship ships, ships, mines, plains, pastures, gas stations, airports, forest farms, hotels, etc