This magnetic switch is used as a door sensor to detects when a closet door is opened turning on the LED Closet Rod(s) lights. Other uses would be for: Pantry Lighting, Interior Cabinet (upper & lower), Sliding doors, Swinging hinge doors, and inside drawers. The switch is encased in a plastic shell and is normally 'open' (no connection between the two wires); the other half is a magnet. When the magnet is less than 13mm (0.5") away, the switch closes turning on the LED light. The choice of switches depends on the total wattage of the LED lights in the circuit.