uxcell 5pcs Recessed NC Security Alarm Door Window Contact Sensor Magnetic Reed Switch
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 ). When make order,pls check carefully!
The reed switch is an electrical switch operated by an applied magnetic field.
Designed for use with alarm systems. Great for use in family and factory window, door. etc.
