A hand-operated siren is a mechanical device used to produce a loud and distinctive warning sound or signal. It is manually operated, usually by rotating a hand-crank, which drives an internal mechanism that generates the siren sound. The siren typically consists of a rotor with holes and a stator with fixed vanes. As the rotor is turned, air passes through the holes, causing the stator vanes to vibrate and create the characteristic siren sound.

Hand-operated sirens are widely used in various applications, including emergency situations, civil defense, fire stations, and industrial facilities. They provide an effective means of alerting people to potential hazards, emergencies, or specific signals in areas where electricity or battery-powered devices may not be practical or available.

Due to their simplicity, reliability, and portability, hand-operated sirens are a valuable tool for emergency preparedness and communication in both urban and remote locations. Their loud and penetrating sound can travel over long distances, making them an essential safety device in various situations where immediate and audible warnings are necessary.