50-70 mm gap Shutter Sensor Roller Door Sensors overhead door contacts with adjustable L bracket

50-70 mm gap Shutter Sensor Roller Door Sensors overhead door contacts with adjustable L bracket            Product Description   Roller shutter sensor,heavy duty overhead door contact sensor, for Mounting on Door Tracks, Adjustable "L" bracket, magnet can be installed in many ways! Armored cable in 380mm or 480mm length Wider Gap for reduced false alarms Closed Loop, open loop and SPDT types Housing: zinc Color: grey Gap:50-70 mm Surface mounted with screws, leads 530mm standard length, with armored cover cable of 380mm or 480mm Note:  1. NC--- here means normally closed. When the door is closed,  the contact of sensor is also closed. If a thief  opens the door,  the contact of sensor will be open , then the   alarm will receive  the  signal.  2. NO--- here means normally open. When the door  is closed ,the contact of the sensor will be open. If a thief opens the door , then the contact of sensor will be changed to closed , stimulating  the alarm to work.  3. COM---here means both normally closed and normally open . The contacts of sensor  can be changed each other .