The shell is made of high quality ABS plastic with matte finish and high-end appearance. When the magnet is close to the switch, the reed contacts are closed and the signal line is connected. If the door is opened, the magnet leaves the switch, the reed contacts are disconnected, and the signal line is interrupted. When someone illegally prizes the roll door open by 2-3 cm, the product immediately sends a signal to the host. The horn in the host will send out a loud alarm sound, so that the illegal can not start. Suitable for shops, stores, garages, supermarket, and other places., Weight: 0.0440924524 pounds, Manufacturer: SYH&AQYE