Hard metal shell, not easy to deform, the sound reaches 100db, the maximum range is 600-800 square meters, and it is farther and safer. Pure copper electromagnetic coil with discontinuity and no electromagnetic interference, strong tapping, stable and long service life. The is coated with electroplating technology to make the material more anti-corrosive and less prone to rust and corrosion. Portable wired power supply, easy to install, can be installed on the wall, ceiling and other installation methods. Choose 12V / 24V / 220V according to the voltage you use. Can be widely used in fire rescue, emergency evacuation, factory alarms, school ringtones, etc., Weight: 0.44 Pounds