Metal Wired Roller Shutter Door Magnetic Contact Reed Switch for Security alarm system Specifics: 1.Color: Silver 2.Material: Metal + Magnet 3.Contact Type: Normally Closed(When there is no magnet or the magnet is far away from the magnetic switch, the magnetic switch is turned off; when there is a magnet close to the magnetic switch, the magnetic switch is turned on) 4.Suitable for: Roller Door,Normal Home/Shop Door 5.Size: AS Shown Features: Brand new and high quality Rated Voltage:100V Simple and convenient for installation The metals electroplates outer shell, double-loop circuit design, performance stable. Circuit is not connected when magnet is near the switch. Special use for metal doors, anti-magnetic interference design. Heavy duty aluminum casting for any weather condition and harsh environment for heavy traffic areas. Dry Contact Output N.C. (door closed) contact opens when the magnet moves away. Compatible with all alarms brands Package included: 1x Door Magnetic Switch Alarm (Screws Included)