uxcell 4mm Inductive Proximity Sensor Switch Detector NPN NO DC 5-30V 200mA 3-Wire SN04-N for 3D Printer Probe Bed Leveling,MCU Board: Amazon.com: Industrial & Scientific
Amazon.com: DIGITEN Hall Sensor Proximity Switch NPN 3-Wires Normally Closed NC with Magnet : Industrial & Scientific
Amazon.com: 2pcs DC 5V NPN NO M12 4mm Sensor LJ12A3-4-Z/BX Inductive Proximity Sensor Switch for 3D Printer CNC Z Probe auto Bed Leveling : Industrial & Scientific