Description:1.Actuation Distance: 25-35mm.Silver gray zinc alloy housing.2.The reed switch is an electrical switch operated by an applied magnetic field.3.Designed for use with alarm systems. Great for use in family and factory window, door. etc.4.Screw Mounted for easily install.5.NC means Normally Closed:When the magnet together, the circuit is conductive( light on ); when the magnet separate, the circuit is not conductive ( light off ). When make order,pls check carefully!Specification:Product Name: Magnetic Door SwitchModel: MC-52Contact Type: NCActuation Distance: 25-35mmMax. Current: 0.5AMax. Power: 10WWorking Voltage: DC100VSize(Approx): 49 x 19 x 9.8mm / 1.93 x 0.75 x 0.39 inch (L*W*H) Hole Dia.: 4.2mmCable Length(Each): 23cm / 9.1-inchMaterial: Zinc Alloy (Housing)Wire Type: 1007UL#22AWGColor: Silver GrayNet Weight: 106gPackage Content:1 x Magnetic Door Switch, 4 x Screws