Electric alarm sensor magnetic door contact switch for window or door

Electric  alarm sensor magnetic door contact switch for window or door         Product Description    surface mounted magnetic switch ideal for metal door/ window, for commercial applications and where a wide gap is needed PY-C58 is designed to be installed in commercial and industrial environments where a rugged sealed unit is required. It is ideal for metal doors, fences and gates. Each model features a high strength extruded alloy-zinc housing and is completely encapsulated in epoxy glue. The  feature wide gap distances and several models to meet any application need. Cored cable or armored cable is available. Housing: zinc material  Color :grey Gap: 40-60mm Wires: 430mm in length is standard, longer wires available   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 .       Dimension(mm)