30pcs RC-33 NC Recessed Wired Security Window Door Contact Sensor Alarm Magnetic Reed Switch White Plastic Ball Bearings alloy and many ther abrasive

alloy and many ther abrasive materials

Package Content: 1 x Post Ball Cap

The added benefit of not only being a dependable fastener

54 inch / 16

dinner and coffee table and so on

30pcs RC-33 NC Recessed Wired Security Window Door Contact Sensor Alarm Magnetic Reed Switch White Plastic Ball Bearings alloy and many ther abrasiveDescription: 1. 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! 2. These are the door contact sensors that are in use with any and all commercial or residential card access systems as well as all security burglar alarm system. 3. Work as an anti theft alarm, perfect for metal door and window.