Feature: 1. EASY TO USE: Hand crank siren consists of a handle and an internal mechanism. With quick rotation of the handle, the mechanism generates a high frequency acoustic vibration that emits a strong alarm sound. The sound transmission range is large and penetrating. 2. ADJUSTABLE VOLUME: The volume of the hand crank alarm is adjustable, the size depends on the speed of the handle rotation, the faster the speed, the louder the sound. Pressing the trigger opens the blades and the alarm will sound louder. 3. STURDY AND DURABLE: This hand crank sound alarm is made of aluminum alloy structure with rustproof paint on the outside, which is more sturdy and wearable, waterproof, durable and has long service life. 4. NO POWER SUPPLY REQUIRED: Manually operated, no installation required, easy to carry. The hand crank horn can provide effective alarms where there is no power support and can be used for emergency alarms at unexpected times to quickly attract the attention of others. 5. APPLICABLE SCENARIOS: It is widely used in various scenarios, such as emergency alarms in case of sudden fire, attack, and emergency for help. The hand crank alarm can also be used as a self guard tool for deterring potential attackers or attracting help from others. Specification: Item Type: Hand Crank Siren Material: Aluminum Alloy Base Size: Approx. 140 x 50mm / 5.5 x 2.0in Hole Spacing: Approx. 110 x 28mm / 4.3 x 1.1in Product Size: Height 328 x 195mm / 12.9 x 7.7in Gross Weight: Approx. 4266g / 9.4lb Communicate Mode: Sound Transmission Alarm Type: On Site Alarm Volume: 125dB(A) at 1m Sound Frequency: 600±20Hz (Depends on the rotation speed) Effective Range: Diameter 2000m/6562ft Application: Widely used in factories, homes, schools, oil depots, warehouses, flood control, disaster relief, public and industrial places, to sound alarms timely in emergency situations and reduce casualties and property loss.. Package List: 1 x Hand Crank Siren1 x Handle Note: Manual measurement, please allow some errors.