Features: brand new and high quality Hand-crank operated emergency alarm is made of high-quality aluminum-alloy material, practical and durable. By manually rotating the handle, the gearbox-of the transmission step by step acceleration to achieve the purpose of sound, the sound depends on the rotation-speed of the handle. Emergency alarm is ideal-for getting people attention, or alerting workers for lunch-time, and also good for many other uses. Can be used for factories, families, schools, flood control, disaster relief, public and industrial occasions. Hand-crank operated alarm is used for emergency warning and easy to carry. Timely warning, reduce the loss of people property and casualties. Specifications: Material: Aluminum-Alloy Size: approx 186x186x170mm/7.32x7.32xx6.69 inches Color: Green/Red Effective Range: diameter 1000m Output Frequency: 550±20Hz Package Includes: 1x Hand-Crank Alarm note: Please allow 1-2cm errors due to manual measurement. Due to the difference betweeen different monitors,the pic-may not reflect the actual color of the item.