Mc-38 Wired Door, Window Sensor Magnetic Switch Home Alarm System Detector. FEATURES: Easy Installation Reliable Performance Good Characteristic of Abrasion-proof Best Choice for You to Protect Family 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 SPECIFICATIONS: Material: ABS Dimension: Approx. 27 X 14 X 8(mm) Switch Pattern: N/C Normally Closed,, Alarm-on-broken Voltage: 100V DC Rated Power: 10W Actuation Distance: 15-25mm Wire Lead: 24 Awg, About 350mm Long Color: White Mounting Method: SMD (by Screws or Double-sided Tapes) Recommendations in the Application: Wooden Door, Window INCLUDES: 5 Pair X Door Magnets ( Note: Packaged Doesn't Included Screws ) . Your order will be shipped from abroad so please allow the necessary time of at least 14 work days for delivery due to ongoing delays in postal deliveries globally.