Protective DeviceThis is a set of magnetic detecting switch used to protect doors and windows for the most part, protective device monitors the opening and closure of doors and windows. High QualityHigh quality magnetic sensor contacts with strong magnetic, sensitive respond and long durability. Easy to installThe wired part often be installed on the fixed door frame and the mating part is mounted at the corresponding place on the door.Simple to install no hassles. Widely UseIdeal entry warning for homes, apartments, mobile homes, dorms, offices, hotel rooms, garages, and more Condition: 100% Brand New Material: Zinc Alloy Color: As Picture Shown Rated Voltage: 12V Rated Current: 120mA Sensing Distance: 50~70mm / 1.9~2.7in Note: Can not be used alone. Should work with the main unit of the alarm system for the alarm.