30pcs RC-33 NC Recessed Wired Door Contact Sensor Alarm Magnetic Reed Switch

0.5A Maximum Switch Current Will make Sense Door Closer at Roughly 15-25mm This Contact Works with Any Access Control or Burglar Alarm System Available NC means Normally Closed:When the magnet together, the circuit is conductive( light on ); when the magnet separate, the circuit is not conductive ( light off ).