Compact and Portable - Lfhelper Hand Crank Alarm is small, lightweight, and easy to install, requiring only 0.15 square meters for operation. No tools needed, making it highly portable. No Power Required - This manual hand crank alarm operates without a power supply, ensuring effective alarm functionality even in areas without power. Simply shake the handle clockwise at 50-80 rpm for a powerful, long-wavelength alarm sound. Versatile Applications - Ideal for various settings including factories, schools, military camps, rescue operations, ships, mines, airports, and more. When power and communication fail, this portable alarm is a reliable solution. Robust Construction - Made of aluminum alloy, this Hand Crank Siren Horn is durable and reliable. With a sound output of 110 dB and an audio frequency of 550 Hz, it provides a loud and attention-grabbing alarm signal. Wide Transmission Range - With a transmission range of 1000 meters, this manual operated metal alarm ensures that the alarm is heard far and wide. Perfect for emergency situations where immediate attention is crucial., Weight: 0.00220462262 Pounds, Manufacturer: Lfhelper