Compact and Lightweight Design - Our portable hand crank siren horn is small, lightweight, and portable, making it easy to install anywhere without any tools required. It only needs 0.15 square meters and a stand for one person to work properly, making it very portable for operation. No Power Supply Needed - The hand crank alarm is designed to provide an effective alarm in places where there is no power supply. Simply manually shake the handle clockwise at a primary speed (50-80 rpm) to produce a majestic sound with a large shock and long wavelength. Practical and Portable - When power and traffic are blocked, other mobile alarms can’t enter the alarm area, making the portable and practical hand crank alarm a very practical alarm solution. Wide Applications - This hand crank siren horn is widely used in factories, schools, open-air military camps, mountain rescue, anti-ship vessels, ships, mines, plains, pastures, gas stations, airports, forest farms, hotels, and more. High Sound Output - With a sound output of 110 ± 2 (dB) and an audio frequency of 550 ± 20 (HZ), this hand crank siren horn is ideal for emergency situations and can be easily heard from a distance., Weight: 2.20462262 Pounds, Manufacturer: Lfhelper