Zinc alloy material---Normally open magnetic switch, the shell material is zinc alloy, hard and safe, strong impact resistance, not easy to damage, can be used for a long time Great tool to deter thieves High accuracy --- Mini door magnetic contact, normally closed magnetic switch with separate contacts, monitors the opening and closing of doors and windows, accuracy is accurate and reliable, a good tool to deter thieves Working principle --- When there is an illegal intrusion through the door and window equipped with the door sensor, the door and the window will disconnect the signal transmission and the host will accept the signal and the alarm magnetic is designed for use with the systems of door and window alarm, such as garages, industrial warehouses and shops, etc.