Check the listing for details. MC-38 Surface Mount Wired NC Door Sensor Alarm Magnetic Reed Switch White New. Condition: New. Listed at 9.91 USD. Description:1.Self-Adhesive Mount, Screw Surface Mount contact, ABS Housing. Long wire lead that can side mounted. 2.Switch Type: 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 ).3.Work as an anti-theft alarm, perfect for wood door and window.4.N.C. means Normally Closed: When the magnet together, the circuit is conductive( light on ); when the magnet separates, the circuit is not conductive ( light off ) Specification:Model: MC-38Contact Type: NC (Normally Closed)Actuation Distance: 10-15mmMax. Current: 0.5AMax. Power: 10WWorking Voltage: DC100VEach Size(Approx): 27 x 14 x 7.8mm / 1.06-inch x 0.55-inch x 0.31-inch (L*W*H)Mounting Hole Diameter: 4mm/0.16-inchCable Length(Each): 26cm / 10.