Features Protective Device: This is a set of magnetic sensing switches used to protect most doors and windows, a protective device monitors the opening and closing of doors and windows. High Quality Materials:Our metal magnetic switch alarm is equipped with durable zinc alloy shell, which provides better anti-rust performance. Widely Used:Our metal door sensor has high quality magnetic sensor contacts, strong magnetism, sensitive response and long service life. Roller shutter door contacts are designed for door and window alarm systems, such as garages, industrial warehouses and shops. Home Security Monitoring Systems. Easy to Install:The wired part of our metal door sensor is usually installed on a fixed door frame, while the corresponding part is installed at the corresponding position on the door. Surveillance cameras. Quality Guarantee: Quality controls strictly in each section during manufacture. If you have any questions about our product, please contact us. We will be very happy to answer your questions and solve problems for you.