Hand Crank Siren Horn Manual Operated Metal Alarm Handheld Air Raid Siren Portable Loud Manual Siren Emergency Safety 1. The siren with manual operation is used for emergency warning and easy to carry. 2. Handheld alarm siren is used for factories, families, schools, flood control, disaster relief,public and industrial occasions. 3. By manually rotating the handle, the transmission step by step acceleration to achieve the purpose of sound, the sound depends on the rotation speed of the handle. 4. It is made of durable aluminium alloy that ia more sturdy and wear resistant. 5. This hand alarm can be warning timely to reduce the loss of people 's property and casualties. Notice: Actual color may be slightly different from the image due to different monitor and light effect Please allow 1-3cm deviation due to manual measurement Specification: Sound Rating: 110+/-2dB(A) @1M Frequency: 550+/-20Hz (Dependent on Rotation Speed) Material: Aluminum alloy Weight: 2.65lb Package size: 170x170x170mm