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How to distinguish between Recessed NO Magnetic Window and Recessed NC Magnetic Window？ The Recessed Magnetic Window is composed of a reed switch and a magnet. 1. The reed switch is normally open（NO）. When there is no magnet approaching, two small pieces of magnetic reed are disconnected; when
the magnet is close, two small pieces of magnetic reed are connected. This is a normally open Recessed Magnetic Window（NO）. Switch Pattern:normally open (NO), when the door(magnet) closed, the switch keeps connecting 
2. The reed switch is normally closed（NC）. Two small pieces of magnetic reed are connected when there is no magnet approaching.
Two magnets are separated when a magnet approaches. This is a normally closed Recessed Magnetic Window(NC) Switch Pattern:normally closed (NC), when the door closed, the switch are separated. 
Features:
Pattern：normally Colosed(NC), when the door closed, the switch don't keep connecting
Size: Part A: 50mm x 18mm x 10mm; Part B: 50mm x 18mm x 10mm;
Alarm time: 5 seconds
Material: aluminium alloy
Output：COM/NC
Operating Current: 500mA
2PCS/1LOT
Application:
Mainly used for roller shutter/rolling door; also applied to other doors and windows
Installation:
Stick part A (magnetic bar) on the edge of the roller shutter/rolling door, and stick part B on the fixed frame of roller shutter/rolling door
Pictures:
 
 
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