This machine is characterized by no need for power supply, compact structure and lightweight easily to be taken along, strong sound and low frequency, universally recognized signals, shutter mechanism for signal choice. Hand operated siren is designed to provide effective warning in applications where there is no power supply such as Civil defence. Camp sites. Mountain rescue. Frontier sentry and coast guard warning ,etc.It is powered by operating its handle, and the hand operating velocity would determine its output frequency. The sound window is equipped with shutter baffle which can quickly shut the sound window, obstacle the sound, and signals differently. As lightweight, it can be easily transported to remote locations and folds up to a small size for ease of handling Model:LK120 Sound rating:120?dB Output frequency:600?0Hz,depends on the hand operating velocity Structure: aluminium alloy Net weight:8.5Kg Packing measure: 450*580*370mm Effective scope: semidiameter of 400m