Differences of NC, NO, NC/NO
Normally Closed(NC): When the switch is close to the magnet, the circuit is conductive(light on); when the switch is separated from the magnet, the circuit is not conductive(light off).
Normally Opened(NO): When the switch is separated from the magnet, the circuit is conductive(light on); When the switch is close to the magnet, the circuit is not conductive(light off).
NC/NO Combined: The switch has 3 contact types: NC/NO/COM, you can choose to connect two of the contacts(NC-COM or NO-COM).

PLEASE NOTE
A magnetic door contact can only provide a switching signal to the device. It cannot directly load the power supply and cannot be directly connected to the lamp.

Specifications:
Model: MC-31
Contact Type: NC/NO/COM
Maximum Sensor Sensitivity: 18mm(+/-8mm)
Load Current: 150mA
Maximum Voltage: 100V DC
Mounting Hole Distance: 52mm / 2.05inch
Size(Approx.):
64 x 20 x 13mm / 2.52 x 0.79 x 0.51inch (L*W*H)
64 x 13 x 13mm / 2.52 x 0.51 x 0.51inch (L*W*H)
Housing Material: ABS

Package Content:
5pcs x Magnetic Door Switch
20pcs x Mounting Screws