Features: 1.Pure copper electromagnetic coil with discontinuity and no electromagnetic interference. 2.Strong tapping, stable operation and long service life. 3.Hard metal shell, not easy to deform, the sound reaches 100db, and it is farther and safer. 4.The surface is coated with electroplating technology to make the material more anti?corrosive and less prone to rust and corrosion. 5.Portable wired power supply, easy to install, can be installed on the wall, ceiling and other installation methods. Specification: Features:_x000D_ _x000D_ Pure copper electromagnetic coil with discontinuity and no electromagnetic interference. _x000D_ Strong tapping, stable operation and long service life. _x000D_ Hard metal shell, not easy to deform, the sound reaches 100db, and it is farther and safer. _x000D_ The surface is coated with electroplating technology to make the material more anti-corrosive and less prone to rust and corrosion. _x000D_ Portable wired power supply, easy to install, can be installed on the wall, ceiling and other installation methods. _x000D_ Choose 12V DC / 24V / 220V according to the voltage you use. _x000D_ _x000D_ Specifications:_x000D_ Condition: Brand New_x000D_ Color: Red_x000D_ Material: Metal_x000D_ Size: 4 inches(100mm)_x000D_ Power Mode: External_x000D_ Optional Voltage: 220V/12V DC/24V_x000D_ Alarm Volume: 100db_x000D_ Surface Treatment: Electroplating_x000D_ _x000D_ Package List:_x000D_ 1 * Fire Alarm Bell PackageList: 1 * FireAlarm Bell