Inductive Proximity Switch Type: SN04-N, 3 Wire NPN NO. Detecting Distance: 4mm. Supply Voltage: 5-30VDC, Current Output: 300mA. LED working indicator: signal indicator, when sensing metal objects the light is on for normally open, the light is off for normally closed. Wiring Method: Brown connect to Positive, Blue connect to Negative, Black connect to Load (signal output). When proximity switch is close to some target object, it will send out control signal. Widely used for machine tool industry, frequency counters and other automatic control system, or you can use it for DIY 3D Printer. Material: plastic colour: As Shown Package Contents: 20 x inductive proximity switch with TL PL SN bracket Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.