Specification Brand : uxcell BulletPoint1 : Country of Manufacture: CHINA; Material: Plastic, Electronic Parts; Net Weight: 23g BulletPoint2 : Package Content: 1 x Magnetic Door Switch Sets, Installation Screws; Type: /; Rated Voltage: DC 100V BulletPoint3 : Rated Current: 500mA; Rated Power: /; Wire Length: / BulletPoint4 : Main Color: White; Contact Type: NC(normal closed type); Operating Distance: 17mm-25mm BulletPoint5 : Big One Size(Approx): 64 x 20 x 13mm / 2.5" x 0.8" x 0.51"(L*W*H); Small One Size(Approx): 64 x 13 x 13mm / 2.5" x 0.5" x 0.51" (L*W*H) CircuitType : 1-way Color : White ConnectivityProtocol : X-10 ConnectorType : 2.5,screws ControlMethod : touch CurrentRating : 0.25 amps ExternallyAssignedProductIdentifier1 : 046843572472 ExternallyAssignedProductIdentifier2 : 0046843572472 ExternallyAssignedProductIdentifier3 : 00793574633131 IncludedComponents : One (1) Reed Switch/Sensor Assembly InternationalProtectionRating : 100 ItemName : uxcell Door Window Normal Closed Contact Security Safety Alarm Magnetic Sensor Reed Switch Sets ItemPackageDimensions_Height : 21.7 centimeters ItemPackageDimensions_Length : 3.8 centimeters ItemPackageDimensions_Width : 13.1 centimeters ItemPackageQuantity : 1 ItemTypeKeyword : reed-switches LightType : Non-Illuminated LowerTemperatureRating : -40 degrees_celsius Manufacturer : uxcell Material : Plastic ModelNumber : a17031000ux0029 MountingType : Door Mount NumberOfItems : 1 NumberOfPositions : 1 OperatingVoltage : 100 volts OperationMode : Plug PackageLevel : unit PartNumber : a17031000ux0029 ProductDescription : Switch Type: NC(normal closed type), the circuit is closed normally, and, that if a magnet not near it, the circuit open. The Reed Switch is an electrical switch operated by an applied magnetic field. It was invented at Bell Telephone Laboratories in 1936 by W. B. Ellwood. It consists of a pair of contacts on ferrous metal reeds in a hermetically sealed glass envelope. There are two types of reed switches: normally open reed switches and normally closed reed switches. The metal reeds on a normally open switch stay open when there is no magnet near the switch. In the presence of a magnetic field, the contacts of a normally-open reed switch will close. A normally-closed reed switch is closed when it is not near a magnet; as a magnet is brought close to it, a normally-closed switch will open.