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Amazon.com: uxcell 4mm Inductive Proximity Sensor Switch Detector PNP NO DC 6-36V 200mA 3-Wire PR12-4DP for 3D Printer Probe Bed Leveling,MCU Board : Industrial & Scientific
Amazon.com: CONTRINEX DW-AV-623-C5-276 EXT Range, Rectangular INDUCTIVE Sensor, PNP N.O. 3-Wire DC I O Link, SUB-Miniature 5 MM Width Rectangular, INDUCTIVE Sensor : Industrial & Scientific